publications
2025
- Real-Time Sea State Estimation for Wave Energy Converter Control via Machine LearningTanvir Alam Shifat, Ryan Coe, Giorgio Bacelli, and Ted BrekkenApplied Sciences, 2025
Wave energy converters (WECs) harness the untapped power of ocean waves to generate renewable energy, offering a promising solution to sustainable energy. An optimal WEC control strategy is essential to maximize power capture that dynamically adjusts system parameters in response to rapidly changing sea states. This study presents a novel control approach that leverages neural networks to estimate sea states from onboard WEC measurements such as position, velocity, and force. Using a point absorber WEC device as a test platform, our proposed approach estimates sea states in real-time and subsequently adjusts PID controller gains to maximize energy extraction. Simulation results across diverse sea conditions demonstrate that our strategy eliminates the need for external wave monitoring equipment while maintaining power capture efficiency. The results show that our neural network-based control technique can improve power capture by 25.6% while significantly reducing system complexity. This approach offers a practical alternative for WEC deployments where direct wave measurements are either infeasible or cost prohibitive.
@article{Shifat:2025aa, article-number = {5772}, author = {Shifat, Tanvir Alam and Coe, Ryan and Bacelli, Giorgio and Brekken, Ted}, date-added = {2025-10-24 09:46:28 -0600}, date-modified = {2025-10-24 09:47:05 -0600}, doi = {10.3390/app15105772}, issn = {2076-3417}, journal = {Applied Sciences}, number = {10}, title = {Real-Time Sea State Estimation for Wave Energy Converter Control via Machine Learning}, url = {https://www.mdpi.com/2076-3417/15/10/5772}, volume = {15}, year = {2025}, bdsk-url-1 = {https://www.mdpi.com/2076-3417/15/10/5772}, bdsk-url-2 = {https://doi.org/10.3390/app15105772} } - Benchmark of numerical modeling approaches on the systematic performance evaluation of wave energy convertersJian Tan, Ryan G. Coe, and George LavidasApplied Ocean Research, 2025
Different numerical modeling methods have been developed and applied to evaluate a variety of performance indicators of wave energy converters (WECs), including the power performance, structural loads, levelized cost of energy, etc. Based on the modeling fidelity, the commonly used numerical modeling approaches can be classified as linear modeling, weakly nonlinear modeling and fully nonlinear modeling approaches. Each method differs in accuracy and computational efficiency, making them suitable for different stages of WEC design. However, the selection of modeling approach could significantly impact evaluation outcomes. For instance, simplified linear models may underestimate structural loads or overestimate energy production in some operational conditions, potentially leading to less cost-effective designs. Given the widespread utilization of these models, it is essential to understand the uncertainties brought by them in performance evaluations. This work is dedicated to benchmarking different linear-potential-flow-based numerical models for evaluating the systematic performance of WECs. Three representative numerical modeling approaches are considered in this work, including linear frequency-domain modeling, statistically linearized spectral-domain modeling and Cummins equation-based nonlinear time-domain modeling. A generic point absorber WEC is considered as the research reference in this work, and different sea sites are taken into account. The numerical models are utilized to predict critical performance indicators, including power performance, the annual energy production, the capacity factor, the levelized cost of energy and the PTO fatigue loads. By comparing the results, this work identifies the uncertainties associated with different modeling approaches in evaluating WEC performance.
@article{Tan:2025aa, author = {Tan, Jian and Coe, Ryan G. and Lavidas, George}, date-added = {2025-10-24 09:42:55 -0600}, date-modified = {2025-10-24 09:43:14 -0600}, doi = {10.1016/j.apor.2025.104725}, issn = {0141-1187}, journal = {Applied Ocean Research}, keywords = {Numerical modeling, Wave energy converter, Power, Fatigue, Levelized cost of energy}, pages = {104725}, title = {Benchmark of numerical modeling approaches on the systematic performance evaluation of wave energy converters}, url = {https://www.sciencedirect.com/science/article/pii/S0141118725003116}, volume = {162}, year = {2025}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S0141118725003116}, bdsk-url-2 = {https://doi.org/10.1016/j.apor.2025.104725} } - System identification techniques applied to a laboratory scale WEC point absorberBret Bosma, Courtney Beringer, Ryan Coe, Giorgio Bacelli, Daniel Gaebele, Dominic Forbush, and Bryson RobertsonIn Proceedings of the European Wave and Tidal Energy Conference (EWTEC2025), Oct 2025
Control is a necessary and challenging task in maximizing the energy harvesting from WECs. Tuning controllers using a brute force method can be time consuming and inefficient. This paper describes a system identification technique for impedance matching used to inform a proportional integral (PI) control methodology implemented on the Lab Upgrade Point Absorber (LUPA) WEC. Testing at the O.H. Hinsdale Wave Research Laboratory at Oregon State University with LUPA is detailed outlining the identification procedure using multisine bandlimited white noise to generate an intrinsic impedance model of the WEC. Validation tests are then described applying the resulting control strategy. Results summarize the average power output for four regular wave cases with a matrix of damping and stiffness values centered on the impedance matching results. The proposed control methodology and tuning process has the potential to streamline the maximum power generation from WECs. The paper also gives more insight into the characterization of the LUPA device and will help researchers better take advantage of the open-source experimental model for future research.
@inproceedings{Bosma:2025aa, address = {Madeira, Portugla}, author = {Bosma, Bret and Beringer, Courtney and Coe, Ryan and Bacelli, Giorgio and Gaebele, Daniel and Forbush, Dominic and Robertson, Bryson}, booktitle = {{Proceedings of the European Wave and Tidal Energy Conference (EWTEC2025)}}, date-added = {2025-10-24 09:37:57 -0600}, date-modified = {2025-10-24 09:41:47 -0600}, doi = {10.36688/ewtec-2025-826}, month = oct, title = {System identification techniques applied to a laboratory scale WEC point absorber}, url = {https://doi.org/10.36688/ewtec-2025-826}, volume = {16}, year = {2025}, bdsk-url-1 = {https://doi.org/10.36688/ewtec-2025-826} } - Frequency array and wave phase realizations for wave energy converter control optimizationJeff Grasberger, Ryan Coe, Daniel T. Gaebele, Michael C. Devin, Carlos A. Michelen Ströfer, and Giorgio BacelliInternational Marine Energy Journal, Oct 2025
Vital to the progression of the wave energy industry is wave energy converter optimization which often relies on frequency-domain evaluations, utilized for efficiency as compared to time-domain. Despite being an integral factor in the resultant solution, the frequency array is rarely described in such studies. This study shows the impacts of the frequency array components and illustrates a general process by which to select a proper frequency array. The main factors to consider are the range and number of frequencies. Furthermore, this study introduces irregular wave phase realizations and suggests the importance of optimizing the system for multiple random sets of wave component phase. Ultimately, the importance of proper selection of both the frequency array and wave phase realizations to the optimization solution is demonstrated for the Pioneer WEC using WecOptTool.
@article{Grasberger:2025ad, author = {Grasberger, Jeff and Coe, Ryan and Gaebele, Daniel T. and Devin, Michael C. and Str{\"o}fer, Carlos A. Michelen and Bacelli, Giorgio}, chapter = {ICOE 2024 special issue papers}, date-added = {2025-10-02 07:28:27 -0600}, date-modified = {2025-10-02 14:31:52 -0600}, doi = {10.36688/imej.8.265-270}, journal = {International Marine Energy Journal}, month = oct, number = {3}, pages = {265-270}, title = {Frequency array and wave phase realizations for wave energy converter control optimization}, url = {https://marineenergyjournal.org/imej/article/view/247}, volume = {8}, year = {2025}, bdsk-url-1 = {https://marineenergyjournal.org/imej/article/view/247}, bdsk-url-2 = {https://doi.org/10.36688/imej.8.265-270} } - Towards an intuitive application of WEC control co-designOcean Engineering, Oct 2025
A simple co-design example in a reduced parameter space is presented for an oscillating flap device. Initially, the WEC geometry and mass properties are considered along with drivetrain gear ratio, inertia, motor constant and stiffness under both PI and optimal control. This parameter space is reduced to those to which performance is most sensitive for a fixed geometry. The gear ratio, drivetrain stiffness, and flap mass are found to be the most impactful design criteria as they can create orders of magnitude variations in power performance. The performance of the optimized system is compared with several sub-optimal variants in terms of electrical and mechanical power capture, transmission coefficients, and transducer power gain. Notably, though substantial power capture improvements are demonstrated when an optimal controller is employed, this power capture remains sensitive to appropriate selections of drivetrain and flap design parameters, implying that control co-design procedures remain necessary for high-performing WECs. A number of practical caveats and extensions to the presented co-design methodology are suggested, including the characterization of system static friction, especially in the presence of high gear ratios.
@article{Forbush:2025ab, author = {Forbush, Dominic D. and Coe, Ryan G. and Bacelli, Giorgio and Gaebele, Daniel T. and Keow, Alicia}, bibtex_show = true, date-added = {2025-07-19 16:16:25 -0600}, date-modified = {2025-10-02 07:43:37 -0600}, doi = {10.1016/j.oceaneng.2025.122762}, issn = {0029-8018}, journal = {Ocean Engineering}, keywords = {Wave energy converter (WEC), Control co-design, Impedance matching}, pages = {122762}, title = {Towards an intuitive application of {WEC} control co-design}, url = {https://www.sciencedirect.com/science/article/pii/S002980182502445X}, volume = {341}, year = {2025}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S002980182502445X}, bdsk-url-2 = {https://doi.org/10.1016/j.oceaneng.2025.122762} } - Designing a small OSWEC for PACWAVEJeff Grasberger, Daniel T. Gaebele, Carlos A. Michelén Ströfer, Giorgio Bacelli, and Ryan G. CoeIn Proceedings of UMERC2025, Aug 2025
Wave energy converters should be intentionally designed for the anticipated deployment conditions. As an example, this paper details the dynamics of an oscillating surge wave energy converter and the design strategy for the PacWave deployment site. Both the vertical location of the center of gravity and the generator power rating are found to impact the performance, with a lower center of gravity leading to better performance, and the generator power rating serving as a method for controlling capacity factor. Furthermore, an analysis of the performance assessment method (clustering and power matrix) identifies the intricacies of selecting an appropriate number of representative sea state clusters and the relationship with the the center of gravity and generator power rating. For the study completed, 4 clusters were sufficient to accurately discern performance trends.
@inproceedings{Grasberger:2025aa, address = {Corvallis, OR}, author = {Grasberger, Jeff and Gaebele, Daniel T. and {Michel{\'e}n Str{\"o}fer}, Carlos A. and Bacelli, Giorgio and Coe, Ryan G.}, bibtex_show = true, booktitle = {Proceedings of UMERC2025}, date-added = {2025-02-05 11:55:20 -0700}, date-modified = {2025-10-24 09:23:35 -0600}, month = aug, title = {Designing a small {OSWEC} for {PACWAVE}}, year = {2025} } - Streamlined Experimental Approach to System Identification of WEC Dynamics and Excitation CharacteristicsDaniel Gaebele, Ryan Coe, Giorgio Bacelli, Dominic Forbush, Bret Bosma, Courtney Beringer, Bryson Robertson, and Pedro LomonacoIn International Conference on Ocean, Offshore and Arctic Engineering (OMAE2025), Jun 2025
Understanding the dynamics of wave energy converters (WECs) is crucial for optimizing their design and performance. Empirically-based modeling can capture complex dynamics that are otherwise difficult to model with first principles, however collecting empirical test data typically involves long, costly testing campaigns. In this study we present the system identification and validation of a multi-input, single-output model of the Lab Upgrade Point Absorber (LUPA). The total testing duration of approximately 2 hours demonstrates significant efficiency compared to traditional week-long testing campaigns. We use a single experimental dataset to derive both the excitation transfer function and intrinsic admittance transfer function, which we express in a non-parametric form relative to the power take off (PTO) degree of freedom (DOF). The dataset contains a series of six trials, with two distinct power levels in the multisine excitation signals for each input. The inputs are the PTO force signal for active actuation and the concurrently generated irregular waves, implemented with white noise (WN) and pink noise (PN) spectra, respectively. For each power level we implemented the input signals with three different phase vectors. Validation experiments showed good agreement (approx. 70% goodness-of-fit) with the identified models, indicating the effectiveness of the approach.
@inproceedings{Gaebele:2025ab, address = {Vancouver, British Columbia, Canada}, author = {Gaebele, Daniel and Coe, Ryan and Bacelli, Giorgio and Forbush, Dominic and Bosma, Bret and Beringer, Courtney and Robertson, Bryson and Lomonaco, Pedro}, bibtex_show = true, booktitle = {International Conference on Ocean, Offshore and Arctic Engineering (OMAE2025)}, date-added = {2025-01-14 10:06:04 -0700}, date-modified = {2025-10-02 07:37:41 -0600}, doi = {10.1115/OMAE2025-156997}, eprint = {https://asmedigitalcollection.asme.org/OMAE/proceedings-pdf/OMAE2025/88940/V005T09A055/7531858/v005t09a055-omae2025-156997.pdf}, month = jun, pages = {V005T09A055}, publisher = {ASME}, series = {International Conference on Offshore Mechanics and Arctic Engineering}, title = {Streamlined Experimental Approach to System Identification of WEC Dynamics and Excitation Characteristics}, url = {https://doi.org/10.1115/OMAE2025-156997}, volume = {Volume 5: Ocean Renewable Energy}, year = {2025}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2025-156997} } - Powering the Woods Hole X-Spar Buoy with Ocean Wave Energy—A Control Co-Design Feasibility StudyDaniel T. Gaebele, Ryan G. Coe, Giorgio Bacelli, Thomas Lanagan, Paul Fucile, Umesh A. Korde, and John TooleEnergies, Jun 2025
Despite its success in measuring air–sea exchange, the Woods Hole Oceanographic Institution’s (WHOI) X-Spar Buoy faces operational limitations due to energy constraints, motivating the integration of an energy harvesting apparatus to improve its deployment duration and capabilities. This work explores the feasibility of an augmented, self-powered system in two parts. Part 1 presents the collaborative design between X-Spar developers and wave energy researchers translating user needs into specific functional requirements. Based on requirements like desired power levels, deployability, survivability, and minimal interference with environmental data collection, unsuitable concepts are pre-eliminated from further feasibility study consideration. In part 2, we focus on one of the promising concepts: an internal rigid body wave energy converter. We apply control co-design methods to consider commercial of the shelf hardware components in the dynamic models and investigate the concept’s power conversion capabilities using linear 2-port wave-to-wire models with concurrently optimized control algorithms that are distinct for every considered hardware configuration. During this feasibility study we utilize two different control algorithms, the numerically optimal (but acausal) benchmark and the optimized damping feedback. We assess the sensitivity of average power to variations in drive-train friction, a parameter with high uncertainty, and analyze stroke limitations to ensure operational constraints are met. Our results indicate that a well-designed power take-off (PTO) system could significantly extend the WEC-Spar’s mission by providing additional electrical power without compromising data quality.
@article{Gaebele:2025aa, article-number = {4442}, author = {Gaebele, Daniel T. and Coe, Ryan G. and Bacelli, Giorgio and Lanagan, Thomas and Fucile, Paul and Korde, Umesh A. and Toole, John}, bibtex_show = true, date-added = {2024-11-11 11:24:08 -0700}, date-modified = {2025-09-26 09:11:10 -0600}, doi = {10.3390/en18164442}, issn = {1996-1073}, journal = {Energies}, number = {16}, title = {Powering the {Woods Hole X-Spar} Buoy with Ocean Wave Energy---A Control Co-Design Feasibility Study}, url = {https://www.mdpi.com/1996-1073/18/16/4442}, volume = {18}, year = {2025}, bdsk-url-1 = {https://www.preprints.org/manuscript/202507.0985/v1} } - Design Principles for Resonant Wave Energy Converters: Benchmarking Power Capture and FlowAlicia Keow, Jantzen Lee, Giorgio Bacelli, and Ryan G. CoeIEEE Transactions on Energy Conversion, Jun 2025
Control co-design (CCD) in Wave Energy Converters (WECs) integrates the controller, power take-off (PTO), and buoy models during system design to optimize power output. Using the bi-conjugate impedance matching principle, this study models the PTO as a two-port network, revealing impedance matching conditions at the input and output ports as a function of the buoy, PTO, and controller. This study examines the pairing of a flywheel-type pitch resonator PTO within a given buoy constrained by limited space and ballast capacity. The results show that physical constraints imposed by the buoy affect PTO performance. While controller tuning achieves optimal output impedance matching and flywheel inertia is maximized within the buoy’s limitations, the PTO’s input impedance remains smaller than the complex conjugate of the buoy’s intrinsic impedance. This mismatch limits the PTO’s ability to generate sufficient reaction torque, particularly outside the resonance frequency, resulting in narrow-band power transfer. The findings emphasize the need for PTO design modifications to improve input power transfer. Pendulum-based PTO mechanisms are proposed as alternatives to couple with multiple buoy motion modes and improve wave-to-wire efficiency while respecting system constraints.
@article{Keow:2025aa, author = {Keow, Alicia and Lee, Jantzen and Bacelli, Giorgio and Coe, Ryan G.}, bibtex_show = true, date-added = {2024-11-11 11:22:20 -0700}, date-modified = {2025-08-20 17:55:39 -0600}, doi = {10.1109/TEC.2025.3593152}, issn = {1558-0059}, journal = {IEEE Transactions on Energy Conversion}, keywords = {Impedance;Impedance matching;Torque;Generators;Energy exchange;Seaports;Flywheels;Charge coupled devices;Wave energy conversion;Angular velocity;Wave Energy Converter;Power Take-off Design;Design Methodology;Wave-to-Wire Efficiency;Impedance Matching;Control Co-Design;Energy Conversion}, pages = {1-12}, title = {Design Principles for Resonant Wave Energy Converters: Benchmarking Power Capture and Flow}, year = {2025}, bdsk-url-1 = {https://doi.org/10.1109/TEC.2025.3593152} } - A Portable Wave Tank and Wave Energy Converter for Engineering Dissemination and OutreachNicholas Ross, Delaney Heileman, A. Gerrit Motes, Anwi Fomukong, Giorgio Bacelli, Steven J. Spencer, Dominic D. Forbush, Kevin Dullea, and Ryan G. CoeHardware, Jun 2025
Wave energy converters are a nascent energy generation technology that harnesses the power in ocean waves. To assist in communicating both fundamental and complex concepts of wave energy, a small-scale portable wave tank and wave energy converter have been developed. The system has been designed using commercial off-the-shelf components, and all design hardware and software are openly available for replication. This project builds on prior research conducted at Sandia National Laboratories, particularly in the areas of WEC device design and control systems. By showcasing the principles of causal feedback control and innovative device design, SIWEED not only serves as a practical demonstration tool but also enhances the educational experience for users. This paper presents the detailed system design of this tool. Furthermore, via testing and analysis, we demonstrate the basic functionality of the system.
@article{Ross:2025aa, article-number = {5}, author = {Ross, Nicholas and Heileman, Delaney and Motes, A. Gerrit and Fomukong, Anwi and Bacelli, Giorgio and Spencer, Steven J. and Forbush, Dominic D. and Dullea, Kevin and Coe, Ryan G.}, bibtex_show = true, date-added = {2024-10-11 13:45:25 -0600}, date-modified = {2025-08-20 17:59:08 -0600}, doi = {10.3390/hardware3020005}, issn = {2813-6640}, journal = {Hardware}, number = {2}, title = {A Portable Wave Tank and Wave Energy Converter for Engineering Dissemination and Outreach}, url = {https://www.mdpi.com/2813-6640/3/2/5}, volume = {3}, year = {2025}, bdsk-url-1 = {https://www.mdpi.com/2813-6640/3/2/5}, bdsk-url-2 = {https://doi.org/10.3390/hardware3020005} } - Co-design of a wave energy converter through bi-conjugate impedance matchingMechatronics, Jun 2025
As with other oscillatory power conversion systems, the design of wave energy converters can be understood as an impedance matching problem. By representing the wave energy converter as a multi-port network, two separate but related impedance matching conditions can be established. Satisfying these conditions maximizes power transfer to the load. In practice, these impedance matching conditions may be used to influence the design of the system (including the hull, power take-off, controller, mooring, etc.). To this end, this paper considers some example applications of wave energy converter design with the help of the impedance matching framework.
@article{Coe:2025ab, author = {Coe, Ryan G. and Bacelli, Giorgio and Gaebele, Daniel and Keow, Alicia and Forbush, Dominic}, bibtex_show = true, date-added = {2024-09-24 09:08:21 -0600}, date-modified = {2025-08-20 17:33:27 -0600}, doi = {10.1016/j.mechatronics.2025.103395}, issn = {0957-4158}, journal = {Mechatronics}, keywords = {Wave energy converter (WEC), Control co-design, Impedance matching}, pages = {103395}, title = {Co-design of a wave energy converter through bi-conjugate impedance matching}, url = {https://www.sciencedirect.com/science/article/pii/S0957415825001047}, volume = {111}, year = {2025}, bdsk-url-1 = {https://dx.doi.org/10.2139/ssrn.4996206} } - Toward Extending the Life of a Floating Offshore Wind Turbine Using Sheltering From Upstream Wave Energy ConvertersDing Peng Liu, Lance Manuel, and Ryan G. CoeJournal of Offshore Mechanics and Arctic Engineering, May 2025
Offshore renewable energy, derived from wind and waves, is increasingly being considered in many world regions. Co-location of offshore wind turbine and wave energy converter arrays allows the shared use of space and offers beneficial interaction, leading to efficient utilization of marine resources and more sustainable ocean energy solutions. By extracting energy from waves, wave energy converters can reduce hydrodynamic loads on downstream floating offshore wind turbines through sheltering effects, enhancing the structural reliability of the floating offshore wind turbine and extending its service life. To quantify such extension in service life, a comprehensive reliability analysis framework is proposed that incorporates metocean data analysis, fatigue damage assessment, and an integrated reliability-based fatigue life estimation. We employ power take-off matrices of alternative wave energy devices to approximate absorbed wave power in encountered sea states. A metocean data analysis establishes representative sea states for the incident waves and lee waves estimated by subtracting absorbed wave power from the incident power. The open-source time-domain simulation tool, openfast, is employed to compute loads on a downstream floating offshore wind turbine, for sea states of interest. Using selected output stress response time series, fatigue damage is assessed; an extended service life due to effective sheltering for the floating offshore wind turbine is evaluated through the proposed fatigue reliability analysis. Considering three alternatives, our analysis indicates that a 14–25% extension in service life can be achieved using wave energy devices that offer the benefits of sheltering.
@article{Liu:2025ab, author = {Liu, Ding Peng and Manuel, Lance and Coe, Ryan G.}, bibtex_show = true, date-added = {2024-07-11 14:40:45 -0600}, date-modified = {2025-06-25 12:04:56 -0600}, doi = {10.1115/1.4068521}, eprint = {https://asmedigitalcollection.asme.org/offshoremechanics/article-pdf/147/6/061702/7468816/omae-25-1001.pdf}, issn = {0892-7219}, journal = {Journal of Offshore Mechanics and Arctic Engineering}, month = may, number = {6}, pages = {061702}, title = {Toward Extending the Life of a Floating Offshore Wind Turbine Using Sheltering From Upstream Wave Energy Converters}, url = {https://doi.org/10.1115/1.4068521}, volume = {147}, year = {2025}, bdsk-url-1 = {https://doi.org/10.1115/1.4068521} } - Hydrodynamic characterization of the Coastal Pioneer Array ocean observing systemJeff T. Grasberger, Dominic D. Forbush, Johannes Spinneken, Mark Bruggemann, Jantzen Lee, Alex Franks, John Reine, Giorgio Bacelli, Albert J. Plueddemann, and Ryan G. CoeJournal of Ocean Engineering and Marine Energy, May 2025
Ocean observation buoys require relatively small amounts of power, yet traditionally necessitate costly resupply trips for battery replacement. With the offshore location of the buoys and small power requirements, wave energy may be an effective solution for providing consistent and reliable power to support the buoy instrumentation. The US National Science Foundation Ocean Observatories Initiative (OOI) includes arrays of point absorber-like buoy systems used for ocean observation that have been deployed at multiple locations including the Southern Mid-Atlantic Bight. A study is currently underway to design a pitch resonator wave energy converter to supplement existing renewable energy generation for powering observation instrumentation. This paper details field measurements from surface moorings of the OOI Coastal Pioneer Array, which informs the subsequent development of a numerical model for the moored observation system. The model is developed in Wave Energy Converter Simulator (WEC-Sim), which leverages the Simscape multibody solver within the MATLAB/Simulink framework and linear potential flow theory to simulate the hydrodynamic interactions and multibody dynamics in 6 degrees of freedom. Multiple tuning variables are considered to produce a model for the system that matches well with empirical data (about 8% error). The WEC-Sim model will serve as a platform for integrating the pitch resonator wave energy converter concept and deployment preparation (detailed design including power take-off and control systems, response evaluation, etc.).
@article{Grasberger:2025ab, author = {Grasberger, Jeff T. and Forbush, Dominic D. and Spinneken, Johannes and Bruggemann, Mark and Lee, Jantzen and Franks, Alex and Reine, John and Bacelli, Giorgio and Plueddemann, Albert J. and Coe, Ryan G.}, bibtex_show = true, date = {2025/04/28}, date-added = {2024-06-28 11:22:15 -0600}, date-modified = {2025-06-25 12:07:26 -0600}, doi = {10.1007/s40722-025-00392-y}, id = {Grasberger2025}, isbn = {2198-6452}, journal = {Journal of Ocean Engineering and Marine Energy}, title = {{Hydrodynamic characterization of the Coastal Pioneer Array ocean observing system}}, url = {https://link.springer.com/article/10.1007/s40722-025-00392-y}, year = {2025}, bdsk-url-1 = {https://link.springer.com/article/10.1007/s40722-025-00392-y}, bdsk-url-2 = {https://doi.org/10.1007/s40722-025-00392-y} } - Theory, Analysis, and Testing of an Angular Resonator for Wave Energy GenerationJantzen Lee, Alicia Keow, Ryan G. Coe, Giorgio Bacelli, Johannes Spinneken, Steven J. Spencer, and Damian Gallegos-PattersonJournal of Ocean Engineering and Marine Energy, May 2025
This article describes the theory, analysis, and initial bench-top testing of a minimally invasive, rotational resonator designed to produce small amounts of electrical energy for use in oceanic observation buoys. This work details the systems of equations that govern such a resonator, its potential power production, and its predicted effects on the modified motion of the buoy. Finally, a bench-top test apparatus is designed and experimented upon to identify the system and verify the system of equations empirically.
@article{Lee:2025aa, author = {Lee, Jantzen and Keow, Alicia and Coe, Ryan G. and Bacelli, Giorgio and Spinneken, Johannes and Spencer, Steven J. and Gallegos-Patterson, Damian}, bibtex_show = true, date = {2025/02/01}, date-added = {2024-02-07 13:34:05 -0700}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1007/s40722-024-00366-6}, id = {Lee2025}, isbn = {2198-6452}, journal = {Journal of Ocean Engineering and Marine Energy}, number = {1}, pages = {97-107}, title = {Theory, Analysis, and Testing of an Angular Resonator for Wave Energy Generation}, url = {https://link.springer.com/article/10.1007/s40722-024-00366-6}, volume = {11}, year = {2025}, bdsk-url-1 = {https://link.springer.com/article/10.1007/s40722-024-00366-6}, bdsk-url-2 = {https://doi.org/10.1007/s40722-024-00366-6} }
2024
- Bench testing of an early prototype pitch resonator WECRyan G. Coe, Jantzen Lee, Alicia Keow, Giorgio Bacelli, Steven J. Spencer, Johannes Spinneken, Damian Gallegos-Patterson, Elaine Liu, Kevin Dullea, Robert Crandell, Miles Skinner, Casey Nichols, and Rebecca FaoAug 2024
This report describes a series of tests performed on a "pitch resonator’" concept for a wave energy converter. The overall testing campaign goals centered on risk reduction for the pitch resonator wave energy converter concept and model validation. Two modes of testing are captured in this report: one using a single degree of freedom test rig and one in which a six degree of freedom Stewart platform was employed.
@techreport{Coe:2024ab, address = {Albuquerque, NM}, author = {Coe, Ryan G. and Lee, Jantzen and Keow, Alicia and Bacelli, Giorgio and Spencer, Steven J. and Spinneken, Johannes and Gallegos-Patterson, Damian and Liu, Elaine and Dullea, Kevin and Crandell, Robert and Skinner, Miles and Nichols, Casey and Fao, Rebecca}, bibtex_show = true, date-added = {2024-06-14 15:05:02 -0600}, date-modified = {2025-05-12 18:49:17 -0600}, doi = {10.2172/2429934}, institution = {Sandia National Laboratories}, month = aug, number = {SAND2024-10402}, title = {Bench testing of an early prototype pitch resonator {WEC}}, url = {https://www.osti.gov/biblio/2429934}, year = {2024}, bdsk-url-1 = {https://www.osti.gov/biblio/2429934} } - Frequency array and wave phase realizations for wave energy converter control optimizationJeff T. Grasberger, Ryan G. Coe, Daniel T. Gaebele, Michael C. Devin, Carlos A. Michelén Ströfer, and Giorgio BacelliIn International Conference on Ocean Energy (ICOE 2024), Sep 2024
@inproceedings{Grasberger:2024aa, address = {Melbourne, Australia}, author = {Grasberger, Jeff T. and Coe, Ryan G. and Gaebele, Daniel T. and Devin, Michael C. and {Michel{\'e}n Str{\"o}fer}, Carlos A. and Bacelli, Giorgio}, bibtex_show = true, booktitle = {International Conference on Ocean Energy (ICOE 2024)}, date-added = {2024-04-17 11:33:29 -0600}, date-modified = {2025-02-05 12:03:51 -0700}, month = sep, title = {Frequency array and wave phase realizations for wave energy converter control optimization}, year = {2024} } - MASK4 Test ReportDominic D. Forbush, Ryan G. Coe, Timothy Donnelly, Ryan G. Coe, Damian Gallegos-Patterson, Steven J. Spencer, Johannes Spinneken, Jantzen Lee, Robert Crandell, and Kevin DulleaJan 2024
Wave energy converters (WECs) are designed to produce useful work from ocean waves. This useful work can take the form of electrical power or even pressurized water for, e.g., desalination. This report details the findings from a wave tank test focused on that production of useful work. To that end, the experimental system and test were specifically designed to validate models for power transmission throughout the WEC system. Additionally, the validity of co-design informed changes to the power take-off (PTO) were assessed and shown to provide the expected improvements in system performance.
@techreport{Forbush:2024aa, address = {Albuquerque, NM}, author = {Forbush, Dominic D. and Coe, Ryan G. and Donnelly, Timothy and Coe, Ryan G. and Gallegos-Patterson, Damian and Spencer, Steven J. and Spinneken, Johannes and Lee, Jantzen and Crandell, Robert and Dullea, Kevin}, bibtex_show = true, date-added = {2024-03-12 09:30:34 -0600}, date-modified = {2025-10-02 14:46:32 -0600}, doi = {10.2172/2280836}, institution = {Sandia National Laboratories}, keywords = {16 TIDAL AND WAVE POWER}, month = jan, number = {SAND-2024-00121}, title = {{MASK4 Test Report}}, url = {https://www.osti.gov/biblio/2280836}, year = {2024}, bdsk-url-1 = {https://www.osti.gov/biblio/2280836}, bdsk-url-2 = {https://doi.org/10.2172/2280836} } - On extending the life of floating offshore wind turbines via sheltering effects of upstream wave energy convertersDing Peng Liu, Lance Manuel, and Ryan G. CoeIn Proceedings of the ASME 2024 43th International Conference on Ocean, Offshore and Arctic Engineering (OMAE2024), Jun 2024
Offshore renewable energy, derived from wind and waves, is increasingly being considered in many regions of the world. Co-location of offshore wind turbine (OWT) and wave energy converter (WEC) arrays allows the shared use of space and offers beneficial interaction, leading to efficient utilization of marine resources and more sustainable ocean energy solutions. By extracting energy from waves, WECs can offer sheltering effects and reduced hydrodynamic loads on downstream OWTs. This can enhance the structural reliability of the OWTs against fatigue and extend the service life. To quantify such extension in service life, a comprehensive reliability analysis framework is proposed that incorporates metocean data analysis, fatigue damage assessment, and an integrated reliability-based fatigue life estimation. We employ power-take-off matrices of different WEC devices to approximate absorbed wave power in irregular sea states. A metocean data analysis establishes the representative sea states for the incident and lee waves, where lee wave conditions are estimated by subtracting WEC absorbed power absorption from the incident power. The open-source time-domain simulation tool, OpenFAST, is employed to compute motions and loads on a downstream floating offshore wind turbine (FOWT), for sea states of interest. Fatigue damage assessment and associated life estimation are carried using a selected output stress response. An extended service life due to effective sheltering for the FOWT can be evaluated through the proposed fatigue reliability-based analysis that includes uncertainties from metocean conditions. By comparing three different types of WEC devices, the analysis showed a 14% to 25 % extension in service life can be achieved.
@inproceedings{Liu:2024aa, address = {Singapore}, author = {Liu, Ding Peng and Manuel, Lance and Coe, Ryan G.}, bibtex_show = true, booktitle = {Proceedings of the ASME 2024 43th International Conference on Ocean, Offshore and Arctic Engineering (OMAE2024)}, date-added = {2024-02-26 11:32:18 -0700}, date-modified = {2025-08-20 18:01:16 -0600}, doi = {10.1115/OMAE2024-139214}, eprint = {https://asmedigitalcollection.asme.org/OMAE/proceedings-pdf/OMAE2024/87790/V002T02A053/7360744/v002t02a053-omae2024-139214.pdf}, month = jun, number = {OMAE2024-139214}, organization = {ASME}, pages = {V002T02A053}, series = {International Conference on Offshore Mechanics and Arctic Engineering}, title = {On extending the life of floating offshore wind turbines via sheltering effects of upstream wave energy converters}, url = {https://doi.org/10.1115/OMAE2024-139214}, volume = {Volume 2: Structures, Safety, and Reliability}, year = {2024}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2024-139214} } - High-dimensional control co-design of a wave energy converter with a novel pitch resonator power takeoff systemMichael C. Devin, Daniel T. Gaebele, Carlos A. Michelén Ströfer, Jeff T. Grasberger, Jantzen Lee, Ryan G. Coe, and Giorgio BacelliOcean Engineering, Sep 2024
Researchers are exploring adding wave energy converters to existing oceanographic buoys to provide a predictable source of renewable power. A ”pitch resonator” power take-off system has been developed that generates power using a geared flywheel system designed to match resonance with the pitching motion of the buoy. However, the novelty of the concept leaves researchers uncertain about various design aspects of the system. This work presents a novel design study of a pitch resonator to inform design decisions for an upcoming deployment of the system. The assessment uses control co-design via WecOptTool to optimize control trajectories for maximal electrical power production while varying five design parameters of the pitch resonator. Given the large search space of the problem, the control trajectories are optimized within a Monte Carlo analysis to identify optimal designs, followed by parameter sweeps around the optimum to identify trends between the design parameters. The gear ratio between the pitch resonator spring and flywheel are found to be the most sensitive design variables to power performance. The assessment also finds similar power generation for various sizes of resonator components, suggesting that correctly designing for optimal control trajectories at resonance is more critical to the design than component sizing.
@article{Devin:2024aa, author = {Devin, Michael C. and Gaebele, Daniel T. and Str{\"o}fer, Carlos A. Michel{\'e}n and Grasberger, Jeff T. and Lee, Jantzen and Coe, Ryan G. and Bacelli, Giorgio}, bibtex_show = true, date-added = {2024-02-07 13:37:15 -0700}, date-modified = {2024-11-11 11:18:47 -0700}, doi = {10.1016/j.oceaneng.2024.119124}, issn = {0029-8018}, journal = {Ocean Engineering}, keywords = {Wave energy converter, Control co-design, Optimization, Power take-off, Central Pioneer Array, WecOptTool}, month = sep, pages = {119124}, title = {High-dimensional control co-design of a wave energy converter with a novel pitch resonator power takeoff system}, url = {https://www.sciencedirect.com/science/article/pii/S0029801824024624}, volume = {312}, year = {2024}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S0029801824024624}, bdsk-url-2 = {https://doi.org/10.1016/j.oceaneng.2024.119124} } - Analysis on Evaluations of Monterey Bay Aquarium Research Institute’s Wave Energy Converter’s Field Data Using WEC-Sim and Gazebo: A Simulation Tool ComparisonChris Dizon, Ryan G. Coe, Andrew Hamilton, Dominic D. Forbush, Michael Anderson, Ted Brekken, and Giorgio BacelliApplied Sciences, Sep 2024
Although many studies have validated wave energy converter (WEC) numerical models against scaled prototype experimental data, there remains a notable lack of validation using data from full-scale deployed WECs. This paper compares two numerical models of Monterey Bay Aquarium Research Institute’s Wave Energy Converter (MBARI-WEC), a two-body point absorber with an electro-hydraulic power take-off system (PTO). The models are implemented in WEC-Sim/Simscape and Gazebo Simulator. A statistical analysis of the models was performed, and field results were obtained to compare the models’ accuracy in predicting the RMS piston velocity, RMS motor speed, and mean electric power compared to field data for 56 observations across varying sea states. The Gazebo model demonstrated a closer agreement across all three parameters for a majority of the observations. When compared to the field data, the Gazebo and WEC-Sim models exhibited average mean electric power overestimations of 13% and 22%, respectively.
@article{Dizon:2024aa, article-number = {11169}, author = {Dizon, Chris and Coe, Ryan G. and Hamilton, Andrew and Forbush, Dominic D. and Anderson, Michael and Brekken, Ted and Bacelli, Giorgio}, bibtex_show = true, date-added = {2024-02-07 13:31:27 -0700}, date-modified = {2024-12-04 09:12:08 -0700}, doi = {10.3390/app142311169}, issn = {2076-3417}, journal = {Applied Sciences}, number = {23}, title = {{Analysis on Evaluations of Monterey Bay Aquarium Research Institute's Wave Energy Converter's Field Data Using WEC-Sim and Gazebo: A Simulation Tool Comparison}}, url = {https://www.mdpi.com/2076-3417/14/23/11169}, volume = {14}, year = {2024}, bdsk-url-1 = {https://www.mdpi.com/2076-3417/14/23/11169}, bdsk-url-2 = {https://doi.org/10.3390/app142311169} } - Co-design of a wave energy converter for autonomous powerRyan G. Coe, Michael C. Devin, Carlos A. Michelén Ströfer, Jantzen Lee, Giorgio Bacelli, Alicia Keow, Daniel T. Gaebele, Jeff Grasberger, Steven J. Spencer, Johannes Spinneken, Vincent S. Neary, and Brek MeurisIn 15th IFAC Conference on Control Applications in Marine Systems, Robotics and Vehicles (IFAC-CAMS), Sep 2024
A “bolt-on” wave energy converter is designed to provide power for sensors on an existing oceanographic buoy. The narrow-banded pitch/roll response of the target oceanographic buoy lends itself to a tuned-resonator design, for which we suggest a novel “pitch resonator” wave energy converter concept. Using a pseudo-spectral method, the performance of the proposed wave energy converter is modeled in the range of sea states expected to be present at the target deployment location to study the effect of flywheel inertia on performance. The results show that the system can marginally meet the desired power demands, but suggest that related design concepts may be worth consideration.
@inproceedings{Coe:2024aa, address = {Blacksburg, VA}, author = {Coe, Ryan G. and Devin, Michael C. and {Michel{\'e}n Str{\"o}fer}, Carlos A. and Lee, Jantzen and Bacelli, Giorgio and Keow, Alicia and Gaebele, Daniel T. and Grasberger, Jeff and Spencer, Steven J. and Spinneken, Johannes and Neary, Vincent S. and Meuris, Brek}, bibtex_show = true, booktitle = {15th IFAC Conference on Control Applications in Marine Systems, Robotics and Vehicles (IFAC-CAMS)}, date-added = {2024-01-29 14:01:55 -0700}, date-modified = {2024-10-30 08:52:43 -0600}, doi = {10.1016/j.ifacol.2024.10.094}, issn = {2405-8963}, keywords = {pseudo-spectral method, autonomous power, wave energy converter (WEC)}, month = sep, number = {20}, organization = {IFAC}, pages = {446-451}, title = {Co-design of a wave energy converter for autonomous power}, url = {https://www.sciencedirect.com/science/article/pii/S2405896324018494}, volume = {58}, year = {2024}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S2405896324018494}, bdsk-url-2 = {https://doi.org/10.1016/j.ifacol.2024.10.094} } - Constrained Pseudo-PI Linear Control of a Wave Energy Converter via Model Predictive ControlTanvir Alam Shifat, Ryan Coe, Giorgio Bacelli, and Ted K.A. BrekkenIn 15th IFAC Conference on Control Applications in Marine Systems, Robotics and Vehicles (IFAC-CAMS), Sep 2024
Due to the inherent unpredictability of ocean waves, an advanced control technique is required to maximize power capture and improve the efficacy of wave energy converters (WECs). This paper investigates three different design approaches to find appropriate weight matrices for a model predictive controller (MPC) that mimics a proportional-integral (PI) controller under unconstrained operation. Later, the optimal design method is used to tune the MPC and implemented with a point absorber WEC model. The results were validated by comparing those with the previously determined linear feedback controller for maximum power capture. This approach enables the PI-emulating MPC to operate as a linear controller without constraints and revert to a conventional MPC under constraints, offering a flexible and effective control solution for WECs.
@inproceedings{Shifat:2024ab, address = {Blacksburg, VA}, author = {Shifat, Tanvir Alam and Coe, Ryan and Bacelli, Giorgio and Brekken, Ted K.A.}, bibtex_show = true, booktitle = {15th IFAC Conference on Control Applications in Marine Systems, Robotics and Vehicles (IFAC-CAMS)}, date-added = {2023-11-13 07:51:37 -0700}, date-modified = {2024-10-30 08:52:32 -0600}, doi = {10.1016/j.ifacol.2024.10.086}, issn = {2405-8963}, keywords = {Model predictive control, wave energy converter, control systems, renewable energy}, month = sep, number = {20}, organization = {IFAC}, pages = {398-403}, title = {Constrained Pseudo-{PI} Linear Control of a Wave Energy Converter via Model Predictive Control}, url = {https://www.sciencedirect.com/science/article/pii/S240589632401841X}, volume = {58}, year = {2024}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S240589632401841X}, bdsk-url-2 = {https://doi.org/10.1016/j.ifacol.2024.10.086} } - A compressible degree of freedom as a means for improving the performance of heaving wave energy convertersAlfred Cotten, Adi Kurniawan, Vincent S. Neary, Ryan G. Coe, and Giorgio BacelliRenewable Energy, Sep 2024
A compressible degree of freedom (CDOF) can provide a means of improving wave power capture by adjusting the system stiffness and providing short-term energy storage, reducing or even eliminating the requirement for two-way electrical power flow as is typical in wave energy control systems. With the overarching goal of investigating and facilitating the application of a CDOF within wave energy converter (WEC) design, this paper focuses primarily on the case of heaving buoys, and on using air volumes to provide the compressible spring effect. Analytical formulae for the natural frequencies are used to gain fundamental insights into the main design considerations. Numerical methods are used to augment this understanding, helping to elucidate the effect of geometric parameters and scale on the required compressible volumes and the efficacy of the CDOF. Beginning with the WaveBot WEC, case studies are then used to demonstrate the design drivers in a more applied context, as well as highlighting the benefit of a self-reacting power take-off (PTO) system. The assimilation of these results with the findings of a detailed literature review culminates in a set of recommendations (or guiding principles) for designing a compressible degree of freedom to improve the performance of a heaving wave energy converter. These recommendations apply both to full-scale WECs, and to the design of scale physical modelling studies for validating the analytical and numerical models.
@article{Cotten:2024aa, author = {Cotten, Alfred and Kurniawan, Adi and Neary, Vincent S. and Coe, Ryan G. and Bacelli, Giorgio}, bibtex_show = true, date-added = {2022-11-29 15:23:55 -0700}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1016/j.renene.2024.120421}, issn = {0960-1481}, journal = {Renewable Energy}, keywords = {Compressible degree of freedom, Heaving wave energy converter, Hydrodynamic modelling, Resonance period lengthening, Wave energy}, pages = {120421}, title = {A compressible degree of freedom as a means for improving the performance of heaving wave energy converters}, url = {https://www.sciencedirect.com/science/article/pii/S0960148124004865}, year = {2024}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S0960148124004865}, bdsk-url-2 = {https://doi.org/10.1016/j.renene.2024.120421} } - Wave Energy Converter Power Take-Off Modeling and Validation From Experimental Bench TestsSimone Giorgi, Ryan G. Coe, Meagan Reasoner, Giorgio Bacelli, Dominic Forbush, Scott Jensen, and Andrew HamiltonIEEE Journal of Oceanic Engineering, Sep 2024
This article describes the implementation of a new numerical model of the power take-off system installed in the Monterey Bay Aquarium Research Institute wave energy converter, a device developed to provide power to various oceanic research missions. The simultaneous presence of hydraulic, pneumatic, and electrical subsystems in the power take-off system represents a significant challenge in forging an accurate model able to replicate the main dynamic characteristics of the system. The validation of the new numerical model is addressed by comparing simulations with the measurements obtained during a series of bench tests. Data from the bench tests show good agreement with the numerical model. The validated model provides deeper insights into the complex nonlinear dynamics of the power take-off system and will support further performance improvements in the future.
@article{Giorgi:2024aa, author = {Giorgi, Simone and Coe, Ryan G. and Reasoner, Meagan and Bacelli, Giorgio and Forbush, Dominic and Jensen, Scott and Hamilton, Andrew}, bibtex_show = true, date-added = {2022-04-05 07:32:52 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1109/JOE.2023.3345903}, journal = {IEEE Journal of Oceanic Engineering}, keywords = {Hydraulic systems;Numerical models;Mathematical models;Permanent magnet motors;Pistons;Force;Springs;Bench tests;modeling;power take-off (PTO);validation;wave energy converter (WEC)}, number = {2}, pages = {446-457}, title = {Wave Energy Converter Power Take-Off Modeling and Validation From Experimental Bench Tests}, url = {https://ieeexplore.ieee.org/document/10436658}, volume = {49}, year = {2024}, bdsk-url-1 = {https://doi.org/10.1109/JOE.2023.3345903} }
2023
- Pioneer WEC concept design reportRyan G. Coe, Jantzen Lee, Giorgio Bacelli, Steven J. Spencer, Kevin Dullea, Albert J. Plueddemann, Derek Buffitt, John Reine, Donald Peters, Johannes Spinneken, Andrew Hamilton, Sahand Sabet, Salman Husain, Dale Jenne, Umesh Korde, Mike Muglia, Trip Taylor, and Eric WadeOct 2023
The “Pioneer WEC” project is targeted at developing a wave energy generator for the Coastal Surface Mooring (CSM) system within the Ocean Observatories Initiative (OOI) Pioneer Array. The CSM utilizes solar photovoltaic and wind generation systems, along with rechargeable batteries, to power multiple sensors on the buoy and along the mooring line. This approach provides continuous power for essential controller functions and a subset of instruments, and meets the full power demand roughly 70% of the time. Sandia has been tasked with designing a wave energy system to provide additional electrical power and bring the CSM up-time for satisfying the full-power demand to 100%. This project is a collaboration between Sandia and Woods Hole Oceanographic Institution (WHOI), along with Evergreen Innovations, Monterey Bay Aquarium Research Institute (MBARI), Eastern Carolina University (ECU), Johns Hopkins University (JHU), and the National Renewable Energy Laboratory (NREL). This report captures Phase I of an expected two phase project and presents project scoping and concept design results. phase project and presents project scoping and concept design results.
@techreport{Coe:2023aa, address = {Albuquerque, NM}, author = {Coe, Ryan G. and Lee, Jantzen and Bacelli, Giorgio and Spencer, Steven J. and Dullea, Kevin and Plueddemann, Albert J. and Buffitt, Derek and Reine, John and Peters, Donald and Spinneken, Johannes and Hamilton, Andrew and Sabet, Sahand and Husain, Salman and Jenne, Dale and Korde, Umesh and Muglia, Mike and Taylor, Trip and Wade, Eric}, bibtex_show = true, date-added = {2024-02-16 13:45:40 -0700}, date-modified = {2024-03-28 12:18:50 -0600}, doi = {10.2172/2280833}, institution = {Sandia National Laboratories}, month = oct, number = {SAND-2023-10861}, title = {{Pioneer WEC concept design report}}, url = {https://www.osti.gov/biblio/2280833}, year = {2023}, bdsk-url-1 = {https://www.osti.gov/biblio/2280833}, bdsk-url-2 = {https://doi.org/10.2172/2280833} } - Wave Energy Converter Direct Drive Power-Take-Off Power Electronic Design to Maximize Power ProductionMadelyn G. Veurink, Wayne W. Weaver, Rush D. Robinett, David G. Wilson, Giorgio Bacelli, and Ryan G. CoeIn 2023 IEEE 24th Workshop on Control and Modeling for Power Electronics (COMPEL), Jun 2023
Wave Energy Converters (WECs) are a form of renewable energy that harvests energy from the waves in a large body of water. WEC systems contain both a mechanical and electrical power take-off (PTO). The systems’ mechanical PTO has been theoretically been optimized to absorb the maximum energy in the wave environment. Still, the electrical PTO of WECs has not yet been optimized to maximize power conversion. The optimal bus voltage and switching frequency of the inverter to maximize energy conversion remains largely unstudied. This study uses Typhoon HIL real-time software to model the mechanical and electrical systems of a WEC operating in an irregular wave environment. The switching frequency of the inverter and the bus voltage is varied to determine the optimal operating conditions for the electrical PTO of the WEC.
@inproceedings{Veurink:2023aa, address = {Ann Arbor, MI}, author = {Veurink, Madelyn G. and Weaver, Wayne W. and Robinett, Rush D. and Wilson, David G. and Bacelli, Giorgio and Coe, Ryan G.}, bibtex_show = true, booktitle = {2023 IEEE 24th Workshop on Control and Modeling for Power Electronics (COMPEL)}, date-added = {2023-07-07 07:40:05 -0600}, date-modified = {2023-09-08 08:25:39 -0600}, doi = {10.1109/COMPEL52896.2023.10221126}, month = jun, organization = {IEEE}, pages = {1-7}, title = {Wave Energy Converter Direct Drive Power-Take-Off Power Electronic Design to Maximize Power Production}, url = {https://ieeexplore.ieee.org/document/10221126}, year = {2023}, bdsk-url-1 = {https://ieeexplore.ieee.org/document/10221126}, bdsk-url-2 = {https://doi.org/10.1109/COMPEL52896.2023.10221126} } - Beta-version Testing and Demonstration of the Design Load Case Generator: A Web-based Tool to Support IEC 62600-2 Standard DesignMark Bruggemann, Graham Penrose, Johannes Spinneken, Vincent S. Neary, Carlos A. Michelen, Seongho Ahn, and Ryan G. CoeIn Proceedings of the 15th European Wave and Tidal Energy Conference (EWTEC2023), Sep 2023
International standards for the design, type-classification and certification of marine energy systems, including wave and current energy converters, are essential for the commercialization of these technologies, but their compliance requires significant effort and resources by project developers; e.g., finding the appropriate met-ocean datasets, processing and analysing this data to estimate the design load conditions, design type-class and load response. Herein we present efforts to address these challenges by developing, beta-testing and demonstrating a web-based tool, the "Design Load Case (DLC) Generator."”" This tool integrates a host of data search, processing and statistical tools to streamline the analysis of design load conditions and to determine the design load requirements as in the International Electrotechnical Commission (IEC) 62600-2 design standard. It is demonstrated for a test DLC analysis case for the Reference Model 3 (RM3) point absorber at the PacWave South test site. This test case highlights some of the challenges determining design load requirements and the benefits of facilitating a complex workflow within a single web-based platform that leverages a diverse set of data processing and statistical tools. The DLC Generator facilitates and streamlines DLC analyses for significant time and cost savings on a variety of tasks in a complex workflow, including site data search and retrieval, data quality control, extreme value statistical analyses, and archiving of dynamic load response model inputs and outputs.
@inproceedings{Bruggemann:2023aa, address = {Bilbao, Spain}, author = {Bruggemann, Mark and Penrose, Graham and Spinneken, Johannes and Neary, Vincent S. and Michelen, Carlos A. and Ahn, Seongho and Coe, Ryan G.}, bibtex_show = true, booktitle = {Proceedings of the 15th European Wave and Tidal Energy Conference (EWTEC2023)}, date-added = {2023-06-08 07:28:35 -0600}, date-modified = {2023-09-08 08:40:52 -0600}, doi = {10.36688/ewtec-2023-419}, month = sep, title = {{Beta-version Testing and Demonstration of the Design Load Case Generator: A Web-based Tool to Support IEC 62600-2 Standard Design}}, url = {https://doi.org/10.36688/ewtec-2023-419}, year = {2023}, bdsk-url-1 = {https://doi.org/10.36688/ewtec-2023-419} } - Hardware-in-the-loop testing of a hydraulic wave energy power take-off systemRyan G. Coe, Jorge A. Leon-Quiroga, Giorgio Bacelli, Steven J. Spencer, Johannes Spinneken, Dominic Forbush, Damian Gallegos-Patterson, Jonathan Berg, and Rachid DarbaliMar 2023
This report describes testing conducted related to the development of a "hydrostatic power take-off" (HPTO) system for a wave energy converter. Tests were conducted with an experimentalelectric motor rig to provide preliminary results and de-risk future testing. Efficiency mappingtests were conducted as well as hardware-in-the-loop (HIL) testing. The results of the efficiencymapping tests provide good insight into how to systematically perform efficiency mapping tests.The HIL testing indicates good overall performance of the system and provides a stepping stonetowards more complete system tests in the future.
@techreport{Coe:2023ab, address = {Albuquerque, NM}, author = {Coe, Ryan G. and Leon-Quiroga, Jorge A. and Bacelli, Giorgio and Spencer, Steven J. and Spinneken, Johannes and Forbush, Dominic and Gallegos-Patterson, Damian and Berg, Jonathan and Darbali, Rachid}, bibtex_show = true, date-added = {2023-03-15 16:04:37 -0600}, date-modified = {2024-10-27 19:22:22 -0600}, doi = {10.2172/2280830}, institution = {Sandia National Laboratories}, month = mar, number = {SAND2023-00788}, title = {Hardware-in-the-loop testing of a hydraulic wave energy power take-off system}, url = {https://www.osti.gov/biblio/2280830}, year = {2023}, bdsk-url-1 = {https://www.osti.gov/biblio/2280830}, bdsk-url-2 = {https://doi.org/10.2172/2280830} } - Maximizing Wave Energy Converter Power Extraction by Utilizing a Variable Negative Stiffness Magnetic SpringJeff T. Grasberger, Ryan G. Coe, Jonathan Bird, Giorgio Bacelli, Alex Hagmüller, and Carlos Michelén StröferIn Proceedings of the 15th European Wave and Tidal Energy Conference (EWTEC2023), Sep 2023
Complex conjugate impedance matching is a key concept for wave energy converter design. Matching the impedance of the power take-off (PTO) system to the complex conjugate of the wave energy converter’s (WEC) impedance ensures efficient transfer of energy from the WEC body motion to electrical power. In low frequency waves, impedance matching often requires a negative PTO stiffness. In this paper, an adjustable stiffness magnetic torsion spring will be presented and modeled to understand its potential to improve WEC performance. The spring has the ability to provide a negative stiffness, allowing the PTO impedance to more closely match the complex conjugate of the WEC impedance at low frequencies. The spring also supports an adjustable stiffness value, meaning it can be tuned according to the incoming wave conditions. The spring’s tunability may put less stress on the rest of the PTO system in wave conditions outside its normal operation zone without sacrificing electrical power output. The adjustable magnetic spring’s effects are modeled and explored in this paper by examining the resultant average annual electrical power and capacity factor. The study suggests that the tunable magnetic spring has the potential to significantly improve capacity factor while maintaining a high average electrical power.
@inproceedings{Grasberger:2023aa, abstractnote = {<p>Complex conjugate impedance matching is a key concept for wave energy converter design. Matching the impedance of the power take-off (PTO) system to the complex conjugate of the wave energy converter's (WEC) impedance ensures efficient transfer of energy from the WEC body motion to electrical power. In low frequency waves, impedance matching often requires a negative PTO stiffness. In this paper, an adjustable stiffness magnetic torsion spring will be presented and modeled to understand its potential to improve WEC performance. The spring has the ability to provide a negative stiffness, allowing the PTO impedance to more closely match the complex conjugate of the WEC impedance at low frequencies. The spring also supports an adjustable stiffness value, meaning it can be tuned according to the incoming wave conditions. The spring's tunability may put less stress on the rest of the PTO system in wave conditions outside its normal operation zone without sacrificing electrical power output. The adjustable magnetic spring's effects are modeled and explored in this paper by examining the resultant average annual electrical power and capacity factor. The study suggests that the tunable magnetic spring has the potential to significantly improve capacity factor while maintaining a high average electrical power.</p>}, address = {Bilbao, Spain}, author = {Grasberger, Jeff T. and Coe, Ryan G. and Bird, Jonathan and Bacelli, Giorgio and Hagm{\"u}ller, Alex and {Michel{\'e}n Str{\"o}fer}, Carlos}, bibtex_show = true, booktitle = {Proceedings of the 15th European Wave and Tidal Energy Conference (EWTEC2023)}, date-added = {2023-02-22 13:15:35 -0700}, date-modified = {2025-08-20 10:39:07 -0600}, doi = {10.36688/ewtec-2023-510}, journal = {Proceedings of the European Wave and Tidal Energy Conference}, month = sep, title = {Maximizing Wave Energy Converter Power Extraction by Utilizing a Variable Negative Stiffness Magnetic Spring}, url = {https://doi.org/10.36688/ewtec-2023-510}, volume = {15}, year = {2023}, bdsk-url-1 = {https://doi.org/10.36688/ewtec-2023-510} } - Control co-design and uncertainty analysis of the LUPA’s PTO using WecOptToolCarlos Michelén Ströfer, Ryan Coe, Daniel Gaebele, Courtney Beringer, Bret Bosma, Bryson Robertson, Giorgio Bacelli, and Michael DevinIn Proceedings of the 15th European Wave and Tidal Energy Conference (EWTEC2023), Sep 2023
Control co-design has been shown to significantly improve the performance of wave energy converters (WEC). By considering the control and WEC design concurrently, the space searched by the optimization routine is greatly expanded which results in better performing devices. Recently, an open-source WEC co-design code, WecOptTool, was released to perform control co-design research and facilitate its adoption in the community. In this study, we use WecOptTool to perform control co-optimization and uncertainty analysis of the LUPA device. The Laboratory Upgrade Point Absorber (LUPA) is a new open-source laboratory-scale WEC that provides a platform for testing new concepts, innovating control schemes, and validating numerical models. The LUPA can be adjusted to different configurations, including changing the number of bodies, the degrees of freedom (DOF), the float and spar geometry, and the diameter of the drive sprocket pulley in the power take off (PTO) system, as well as providing different control algorithms and input waves. The drive sprocket diameter influences the torque vs speed of the generator, which allows for more flexibility in operating under different wave conditions or with different control schemes. In this study we optimize the drive sprocket diameter, while considering the optimal control algorithm for each potential design, to identify the optimal diameter for electric power production at the PacWave South WEC test site. This case study demonstrates several new capabilities of WecOptTool including a multi-body multi-DOF system and multi-directional irregular waves. The PTO dynamics are modeled using first principle methods for a parametrized model of the mechanical subcomponents in combination with generator model obtained using a power-invariant Park transform. The case-study will be made available to serve as a design tool along the LUPA hardware. Users can readily use this model to perform their own design optimization prior to testing with the physical LUPA device. Finally, we use the automatic differentiation capability of WecOptTool to perform a sensitivity and uncertainty analysis of the LUPA device.
@inproceedings{Michelen-Strofer:2023ab, abstractnote = {<p class="FirstParagraph">Control co-design has been shown to significantly improve the performance of wave energy converters (WEC). By considering the control and WEC design concurrently, the space searched by the optimization routine is greatly expanded which results in better performing devices. Recently, an open-source WEC co-design code, WecOptTool, was released to perform control co-design research and facilitate its adoption in the community. In this study, we use WecOptTool to perform control co-optimization and uncertainty analysis of the LUPA device. The Laboratory Upgrade Point Absorber (LUPA) is a new open-source laboratory-scale WEC that provides a platform for testing new concepts, innovating control schemes, and validating numerical models. The LUPA can be adjusted to different configurations, including changing the number of bodies, the degrees of freedom (DOF), the float and spar geometry, and the diameter of the drive sprocket pulley in the power take off (PTO) system, as well as providing different control algorithms and input waves. The drive sprocket diameter influences the torque vs speed of the generator, which allows for more flexibility in operating under different wave conditions or with different control schemes. In this study we optimize the drive sprocket diameter, while considering the optimal control algorithm for each potential design, to identify the optimal diameter for electric power production at the PacWave South WEC test site. This case study demonstrates several new capabilities of WecOptTool including a multi-body multi-DOF system and multi-directional irregular waves. The PTO dynamics are modeled using first principle methods for a parametrized model of the mechanical subcomponents in combination with generator model obtained using a power-invariant Park transform. The case-study will be made available to serve as a design tool along the LUPA hardware. Users can readily use this model to perform their own design optimization prior to testing with the physical LUPA device. Finally, we use the automatic differentiation capability of WecOptTool to perform a sensitivity and uncertainty analysis of the LUPA device.</p>}, address = {Bilbao, Spain}, author = {{Michel{\'e}n Str{\"o}fer}, Carlos and Coe, Ryan and Gaebele, Daniel and Beringer, Courtney and Bosma, Bret and Robertson, Bryson and Bacelli, Giorgio and Devin, Michael}, bibtex_show = true, booktitle = {Proceedings of the 15th European Wave and Tidal Energy Conference (EWTEC2023)}, date-added = {2023-02-09 07:51:06 -0700}, date-modified = {2025-08-20 10:39:59 -0600}, doi = {10.36688/ewtec-2023-288}, journal = {Proceedings of the European Wave and Tidal Energy Conference}, month = sep, title = {Control co-design and uncertainty analysis of the {LUPA}'s {PTO} using {WecOptTool}}, url = {https://doi.org/10.36688/ewtec-2023-288}, volume = {15}, year = {2023}, bdsk-url-1 = {https://doi.org/10.36688/ewtec-2023-288} } - On the state of the art of CFD simulations for wave energy converters within the open-source numerical framework of DualSPHysicsAlejandro Crespo, Bonaventura Tagliafierro, Iván Martı́nez-Estévez, José Domı́nguez, Maite deCastro, Moncho Gómez-Gesteira, Corrado Altomare, Moisés Brito, Francisco Bernardo, Rui Ferreira, Salvatore Capasso, Giacomo Viccione, Nicolas Quartier, Vasiliki Stratigaki, Peter Troch, Irene Simonetti, Lorenzo Cappietti, Malin Göteman, Jens Engström, Giorgio Bacelli, Ryan Coe, Georgios Fourtakas, and Peter StansbyIn Proceedings of the 15th European Wave and Tidal Energy Conference (EWTEC2023), Sep 2023
There are currently several types of devices capable of harnessing wave energy, exploiting a broad variety of physical transformation processes. These devices – known as Wave Energy Converters (WECs) – are developed to maximize their power output. However, there are still uncertainties about their response and survivability to loads induced by adverse environmental conditions, with a consequent increase of the Levelized Cost of Energy (LCOE), which prevents in fact their commercial diffusion. As evidenced by a large body of research, marine renewable energy devices need to have more robust design practices. To address this issue, we propose the CFD-based DualSPHysics toolbox as a support in the design stages. DualSPHysics is high-fidelity software inherently suited to numerically address most challenges posed by multiphysics simulations, which are required to reliably predict WEC response in situations well beyond operational conditions. It should be noted that WECs, generally, may be connected to the seabed and comprise mechanical systems named Power Take-Offs (PTO) used to convert the energy from waves into electricity or other usable energies. To reproduce these features, DualSPHysics benefits from coupling with the multiphysics library Project Chrono and the dynamic mooring model Moordyn+. In this work, the augmented DualSPHysics framework is utilised to simulate a range of very different types of WECs with a variety of elements, such as catenary connections, taut mooring lines, or linear and nonlinear PTO actuators. Version 5.2 of the open-source licensed code was recently released, making the numerical framework publicly available as one unit. This work aims to provide a numerical review of past applications, and to demonstrate how the same open-source code is able to simulate very different technologies. Specifically, this paper proposes routine modeling and validation procedures using the SPH-based solver DualSPHysics applied to five different WEC types: i) a moored point absorber (PA); ii) an oscillating wave surge converter (OWSC); iii) a floating OWSC (so called FOSWEC); iv) a wave energy hyperbaric converter (WEHC); and v) a multi-body attenuator (so called Multi-float M4). For each device listed above, we provide validation proof against physical model data for various components of the floater(s) and PTO related quantities, performed under specific sea conditions that aim to challenge their survivability. Within the scope of this research, we present the WEC response with respect to the degrees of freedom that really matter for each of the floatings due to hydrodynamic interactions (i.e., heave, surge, and pitch), along with quantities more intimately connected to the anchoring systems (e.g., line tension) or the mechanical apparatus (e.g., end-stopper force). The quality of the results, the discussion built upon them and the demonstrated solver exploitability to a wide range of WECs show that one software model can run all cases using the exact same methodology, which is of great value for the marine energy R&D community. Finally, we discuss future research objectives, which include the implementation of automation to apply open control systems and possible applications to subsets of WEC farm arrays and other floating energy harnessing devices.
@inproceedings{Crespo:2023vm, address = {Bilbao, Spain}, author = {Crespo, Alejandro and Tagliafierro, Bonaventura and Mart{\'\i}nez-Est{\'e}vez, Iv{\'a}n and Dom{\'\i}nguez, Jos{\'e} and deCastro, Maite and G{\'o}mez-Gesteira, Moncho and Altomare, Corrado and Brito, Mois{\'e}s and Bernardo, Francisco and Ferreira, Rui and Capasso, Salvatore and Viccione, Giacomo and Quartier, Nicolas and Stratigaki, Vasiliki and Troch, Peter and Simonetti, Irene and Cappietti, Lorenzo and G{\"o}teman, Malin and Engstr{\"o}m, Jens and Bacelli, Giorgio and Coe, Ryan and Fourtakas, Georgios and Stansby, Peter}, bibtex_show = true, booktitle = {Proceedings of the 15th European Wave and Tidal Energy Conference (EWTEC2023)}, date-added = {2023-01-25 11:22:27 -0700}, date-modified = {2025-08-20 10:40:45 -0600}, doi = {10.36688/ewtec-2023-145}, month = sep, title = {On the state of the art of {CFD} simulations for wave energy converters within the open-source numerical framework of {DualSPHysics}}, url = {https://doi.org/10.36688/ewtec-2023-145}, year = {2023}, bdsk-url-1 = {https://doi.org/10.36688/ewtec-2023-145} } - Incorporating Empirical Nonlinear Efficiency Into Control Co-Optimization of a Real World Heaving Point Absorber Using WecOptToolDaniel T. Gaebele, Carlos A. Michelén Ströfer, Michael C. Devin, Jeff T. Grasberger, Ryan G. Coe, and Giorgio BacelliIn Proceedings of the ASME 2023 42nd International Conference on Ocean, Offshore and Arctic Engineering (OMAE2023), Jun 2023
The open-source WecOptTool was developed to make wave energy converter (WEC) control co-design accessible. WecOptTool is based on the pseudo-spectral method which is capable of efficiently dealing with any linear or nonlinear constraints and nonlinear dynamics by solving the WEC optimal control problem in the time domain using a gradient based optimization algorithm. This work1 presents a control co-optimization study of the AquaHarmonics Inc. heaving point absorber WEC sized for ocean deployment to solve practical industry design problems. Components such as the specific type of generator, the hull shape, and the displaced volume are pre-determined. We co-optimize the WEC’s mass versus mooring line pretension in conjunction with the controller. The optimization is subject to the power-take-off (PTO) dynamics and the rated constraints of the components. In particular, the continuous torque rating is implemented as an explicit constraint, a novel approach for WEC optimization. The PTO dynamics are incorporated into the optimization algorithm via a combination of first principle methods (linear drivetrain model) and empirical efficiency maps (electrical generator) represented as a power loss map. This is a practical method applicable to a variety of PTO architectures and transferable to other WECs. A discussion between using an efficiency coefficient versus a power loss map and their implication for the optimization method is presented. This application of WecOptTool represents a real world WEC by combining simplified models with empirical efficiency data. The WEC, as a dynamically coupled, oscillatory system, requires consideration of the time trajectory dependent power loss for optimizing the average electrical power. This objective function, the modelling approach, and the realistic loss terms makes the common practice of artificially penalizing the reactive power needless.
@inproceedings{Gaebele:2023wf, address = {Melbourne, Australia}, author = {Gaebele, Daniel T. and {Michel{\'e}n Str{\"o}fer}, Carlos A. and Devin, Michael C. and Grasberger, Jeff T. and Coe, Ryan G. and Bacelli, Giorgio}, bibtex_show = true, booktitle = {Proceedings of the ASME 2023 42nd International Conference on Ocean, Offshore and Arctic Engineering (OMAE2023)}, date-added = {2023-01-12 14:02:25 -0700}, date-modified = {2025-10-02 07:46:49 -0600}, doi = {10.1115/OMAE2023-103899}, month = jun, pages = {V008T09A067}, title = {{Incorporating Empirical Nonlinear Efficiency Into Control Co-Optimization of a Real World Heaving Point Absorber Using WecOptTool}}, url = {https://asmedigitalcollection.asme.org/OMAE/proceedings-abstract/OMAE2023/86908/V008T09A067/1167388}, volume = {8: Ocean Renewable Energy}, year = {2023}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2023-103899} } - Useful power maximization for wave energy convertersRyan G. Coe, and Giorgio BacelliEnergies, Jun 2023
Wave energy converters (WECs) have enormous potential in providing clean renewable energy with high levels of predictability [...]
@article{Coe:2023ac, article-number = {529}, author = {Coe, Ryan G. and Bacelli, Giorgio}, bibtex_show = true, date-added = {2022-11-01 08:14:47 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.3390/en16010529}, issn = {1996-1073}, journal = {Energies}, number = {1}, title = {Useful power maximization for wave energy converters}, url = {https://www.mdpi.com/1996-1073/16/1/529}, volume = {16}, year = {2023}, bdsk-url-1 = {https://www.mdpi.com/1996-1073/16/1/529}, bdsk-url-2 = {https://doi.org/10.3390/en16010529} } - Control Co-Design of Power Take-off Systems for Wave Energy Converters using WecOptToolCarlos A. Michelén Ströfer, Daniel T. Gaebele, Ryan G. Coe, and Giorgio BacelliIEEE Transactions on Sustainable Energy, Jun 2023
Improved power take-off (PTO) controller design for wave energy converters is considered a critical component for reducing the cost of energy production. However, the device and control design process often remains sequential, with the space of possible final designs largely reduced before the controller has been considered. Control co-design, whereby the device and control design are considered concurrently, has resulted in improved designs in many industries, but remains rare in the wave energy community. In this paper we demonstrate the use of a new open-source code, WecOptTool, for control co-design of wave energy converters, with the aim to make the co-design approach more accessible and accelerate its adoption. Additionally, we highlight the importance of designing a wave energy converter to maximize electrical power, rather than mechanical power, and demonstrate the co-design process while modeling the PTO’s components (i.e., drive-train and generator, and their dynamics). We also consider the design and optimization of causal fixed-structure controllers. The demonstration presented here considers the PTO design problem and finds the optimal PTO drive-train that maximizes annual electrical power production. The results show a 22% improvement in the optimal controller and drive-train co-design over the optimal controller for the nominal, as built, device design.
@article{Michelen-Strofer:2023aa, author = {{Michel{\'e}n Str{\"o}fer}, Carlos A. and Gaebele, Daniel T. and Coe, Ryan G. and Bacelli, Giorgio}, bibtex_show = true, date-added = {2022-08-24 15:57:28 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1109/TSTE.2023.3272868}, journal = {IEEE Transactions on Sustainable Energy}, number = {4}, pages = {2157-2167}, title = {Control Co-Design of Power Take-off Systems for Wave Energy Converters using {WecOptTool}}, url = {https://ieeexplore.ieee.org/document/10114969}, volume = {14}, year = {2023}, bdsk-url-1 = {https://ieeexplore.ieee.org/document/10114969}, bdsk-url-2 = {https://doi.org/10.1109/TSTE.2023.3272868} } - Wave energy conversion using a small tubular free-floating deviceJournal of Ocean Engineering and Marine Energy, Jun 2023
Wave energy devices traditionally tend to be large, as their sizes are often determined by power conversion targets and their operating wave climates. Here we examine a size-constrained device designed to fit within narrow tubes, and using well-known analysis techniques show that converted power amounts may be large enough to meet or exceed the needs of instrumentation to serve a majority of oceanographic and defense ocean measurement needs. The device examined in this paper is designed to fit within, and to be deployed from, torpedo tubes or other equivalently sized cylindrical containers. Examined in this paper is a traditional tubular oscillating water column device, and particular interest here is in designs that lead to optimization of power converted in anticipated wave climates. A two-step design procedure is investigated here, wherein a more approximate two-degree-of-freedom model is first used to identify relative dimensions (of device elements) that optimize power conversion from relative oscillations between the device elements. A more rigorous mathematical model based on the hydrodynamics of oscillating pressure distributions within solid oscillators is then used to provide the hydrodynamic coefficients, forces, and flow rates for the device. These results are next used together with a power take-off model, to provide a quick but rigorous way to estimate the energy conversion performance of the device in various wave climates. A power take-off based on a self-rectifying turbine system is used, and its representative conductance and susceptance values are derived for a chosen geometry and configuration. Calculations are carried out to illustrate the design procedure, and converted power values exceeding ten watts are noted in wind-sea like conditions. Further, performance comparisons with solar panels in Arctic latitudes indicate that such designs may yield considerably better energy conversion during seasons of low insolation. These devices could be designed to convert enough power to perform designated ocean measurement operations while storing any excess energy to support vehicle recharging operations.
@article{Korde:2023aa, author = {Korde, Umesh A. and Gish, L. Andrew and Bacelli, Giorgio and Coe, Ryan G.}, bibtex_show = true, date = {2023/11/13}, date-added = {2022-06-07 14:19:59 -0600}, date-modified = {2023-11-13 07:46:19 -0700}, doi = {10.1007/s40722-023-00299-6}, id = {Korde2023}, isbn = {2198-6452}, journal = {Journal of Ocean Engineering and Marine Energy}, title = {Wave energy conversion using a small tubular free-floating device}, url = {https://doi.org/10.1007/s40722-023-00299-6}, year = {2023}, bdsk-url-1 = {https://doi.org/10.1007/s40722-023-00299-6} } - An efficient and effective WEC power take-off systemJorge A. Leon-Quiroga, Giorgio Bacelli, Dominic D. Forbush, Steven J. Spencer, and Ryan G. CoeIEEE Transactions on Sustainable Energy, Jul 2023
A numerical model for a hydraulic wave energy converter power take-off is developed in this study. The system architecture is described and the mathematical model for each component is presented. The accumulators are not used as energy storage devices. Instead, they are used to reduce the stiffness of the system, increase the response time, and improve the controllability. The numerical model was implemented using MATLAB/Simulink. The design variables selected for this study are the maximum displacement in the hydraulic motors, and the shaft inertia. The effect of these design variables on system performance is studied using latin-hypercube sampling to generate the cases to be simulated. The displacement in the hydraulic devices is used as a control input to adjust the pressure in the hydraulic cylinder and then change the force acting on the floating body. The desired force is calculated by a high level controller that estimates the force value to achieve impedance matching in the WEC. The torque in the electric generator is used to control the shaft speed. The system was designed to actively use reactive power flow to maximize the electric power output in the generator. The model developed in this study is a complete wave-to-wire model based on a co-design approach that considers the effect of all the different subsystems on the dynamic behavior of the whole WEC system. Twelve different wave conditions were tested. The most critical metric for this study is the electric power in the generator, which is the objective function of the optimization that was performed for all the wave conditions defined as case study. The wave-to-wire efficiency, which includes the complete wave energy to electrical energy conversion chain, is also calculated in this work.
@article{Leon-Quiroga:2023aa, author = {Leon-Quiroga, Jorge A. and Bacelli, Giorgio and Forbush, Dominic D. and Spencer, Steven J. and Coe, Ryan G.}, bibtex_show = true, date-added = {2022-01-24 14:31:46 -0700}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1109/TSTE.2023.3237125}, journal = {IEEE Transactions on Sustainable Energy}, month = jul, number = {3}, pages = {1526-1539}, title = {An efficient and effective {WEC} power take-off system}, url = {https://ieeexplore.ieee.org/document/10017387}, volume = {14}, year = {2023}, bdsk-url-1 = {https://ieeexplore.ieee.org/document/10017387}, bdsk-url-2 = {https://doi.org/10.1109/TSTE.2023.3237125} } - The wave energy converter control competition (WECCCOMP): Wave energy control algorithms compared in both simulation and tank testingJohn V. Ringwood, Nathan Tom, Francesco Ferri, Yi-Hsiang Yu, Ryan G. Coe, Kelley Ruehl, Giorgio Bacelli, Shuo Shi, Ron J. Patton, Paolino Tona, Guillaume Sabiron, Alexis Merigaud, Bradley A. Ling, and Nicolas FaedoApplied Ocean Research, Sep 2023
The wave energy control competition established a benchmark problem which was offered as an open challenge to the wave energy system control community. The competition had two stages: In the first stage, competitors used a standard wave energy simulation platform (WEC-Sim) to evaluate their controllers while, in the second stage, competitors were invited to test their controllers in a real-time implementation on a prototype system in a wave tank. The performance function used was based on converted energy across a range of standard sea states, but also included aspects related to economic performance, such as peak/average power, peak force, etc. This paper compares simulated and experimental results and, in particular, examines if the results obtained in a linear system simulation are borne out in reality. Overall, within the scope of the device tested, the range of sea states employed, and the performance metric used, the conclusion is that high-performance WEC controllers work well in practice, with good carry-over from simulation to experimentation. However, the availability of a good WEC mathematical model is deemed to be crucial.
@article{Ringwood:2023aa, author = {Ringwood, John V. and Tom, Nathan and Ferri, Francesco and Yu, Yi-Hsiang and Coe, Ryan G. and Ruehl, Kelley and Bacelli, Giorgio and Shi, Shuo and Patton, Ron J. and Tona, Paolino and Sabiron, Guillaume and Merigaud, Alexis and Ling, Bradley A. and Faedo, Nicolas}, bibtex_show = true, date-added = {2020-10-07 13:56:04 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1016/j.apor.2023.103653}, issn = {0141-1187}, journal = {Applied Ocean Research}, keywords = {Wave energy, Modelling, Control, Estimation, Forecasting, Competition}, month = sep, pages = {103653}, title = {{The wave energy converter control competition (WECCCOMP): Wave energy control algorithms compared in both simulation and tank testing}}, url = {https://www.sciencedirect.com/science/article/pii/S0141118723001943}, volume = {138}, year = {2023}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S0141118723001943}, bdsk-url-2 = {https://doi.org/10.1016/j.apor.2023.103653} }
2022
- On Real-Time Hybrid Testing of Ocean Wave Energy Conversion Systems: An Experimental StudyAli S. Haider, Ted K. A. Brekken, Ryan G. Coe, Giorgio Bacelli, and Alan McCallIEEE Open Journal of Industry Applications, Feb 2022
The growing wave energy sector requires an efficient and flexible testing process for the development phase of wave energy systems. Real-time hybrid testing is a promising technique for the accelerated testing of wave energy conversion systems. This article presents an experimental study on developing a hybrid testing platform for wave energy systems at the Wallace Energy System and Renewables Facility (WESRF) at Oregon State University. The wave energy conversion system is broken down into numeric (i.e., virtual) and physical (i.e., hardware) components. The numeric component involves software components such as the control algorithm for Wave Energy Converter (WEC) and controller for the power electronic converters and numerical models for the WEC device hydrodynamics. The hardware involves an ocean wave emulator testbed, Power Take-Off (PTO) mechanism, power electronics, and instrumentation. The numeric components are implemented in a real-time target machine and are interfaced with the experimental system. A case study implementation of Nonlinear Model Predictive Control (NMPC) is presented for a single degree of freedom heaving nonlinear WEC model with a Permanent Magnet Synchronous Generator (PMSG) as a PTO system. A Field-Oriented Control (FOC) algorithm controls the PMSG-PTO generation using a three-phase Integrated Intelligent Power (IIP) module converter. A demonstration of the proposed hybrid testing setup is provided.
@article{Haider:2022tq, author = {Haider, Ali S. and Brekken, Ted K. A. and Coe, Ryan G. and Bacelli, Giorgio and McCall, Alan}, bibtex_show = true, date-added = {2022-04-04 09:36:36 -0600}, date-modified = {2023-09-08 08:28:44 -0600}, doi = {10.1109/OJIA.2022.3148388}, journal = {IEEE Open Journal of Industry Applications}, month = feb, pages = {30-40}, title = {On Real-Time Hybrid Testing of Ocean Wave Energy Conversion Systems: An Experimental Study}, url = {https://ieeexplore.ieee.org/document/9705552/}, volume = {3}, year = {2022}, bdsk-url-1 = {https://doi.org/10.1109/OJIA.2022.3148388} } - Mini-DAQ: A lightweight, low-cost, high resolution, data acquisition system for wave energy converter testingHardwareX, Oct 2022
As part of the development process, scaled testing of wave energy converter devices are necessary to prove a concept, study hydrodynamics, and validate control system approaches. Creating a low-cost, small, lightweight data acquisition system suitable for scaled testing is often a barrier for wave energy converter developers’ ability to test such devices. This paper outlines an open-source solution to these issues, which can be customized based on specific needs. This will help developers with limited resources along a path toward commercialization.
@article{Bosma:2022uq, author = {Bosma, Bret and Coe, Ryan and Bacelli, Giorgio and Brekken, Ted and Gunawan, Budi}, bibtex_show = true, date-added = {2022-04-04 09:34:30 -0600}, date-modified = {2023-09-08 08:27:51 -0600}, doi = {10.1016/j.ohx.2022.e00332}, issn = {2468-0672}, journal = {HardwareX}, keywords = {System monitoring, Data logging, Open hardware, EtherCAT, Renewable energy, Energy, Electrical engineering, Wave energy}, month = oct, pages = {e00332}, title = {{Mini-DAQ: A lightweight, low-cost, high resolution, data acquisition system for wave energy converter testing}}, url = {https://www.sciencedirect.com/science/article/pii/S2468067222000773}, volume = {12}, year = {2022}, bdsk-url-1 = {https://doi.org/10.1016/j.ohx.2022.e00332} } - A Review of Standards for the Blue Economy – Gaps & ChallengesRoger Basu, Krish Thiagarajan Sharman, Ryan G. Coe, and Tobias DewhurstIn SNAME Maritime Convention, Sep 2022D011S005R001
A key ingredient in the design of structures and systems for the Blue Economy is engineering standards (used here as a blanket term for codes, Rules, recommended practices etc.). The focus in this paper is standards applicable to offshore wind, marine renewables, and open-ocean aquaculture. Standards for oil and gas offshore structures are used as a starting point. Developing and maintaining standards for any engineering discipline is always challenging and more so for rapidly developing sectors such as those associated with the Blue Economy. This paper presents a general discussion of engineering standards and the current state of standards for the Blue Economy. This includes a selective survey of relevant standards; the current and anticipated challenges and how much progress has been made towards developing the required documents.
@inproceedings{Basu:2022vl, address = {Houston, TX, USA}, author = {Basu, Roger and Sharman, Krish Thiagarajan and Coe, Ryan G. and Dewhurst, Tobias}, bibtex_show = true, booktitle = {SNAME Maritime Convention}, date-added = {2022-01-26 10:25:02 -0700}, date-modified = {2023-11-27 06:03:55 -0700}, doi = {10.5957/SMC-2022-061}, eprint = {https://onepetro.org/SNAMESMC/proceedings-pdf/SMC22/1-SMC22/D011S005R001/3007934/sname-smc-2022-061.pdf}, month = sep, note = {D011S005R001}, series = {SNAME Maritime Convention}, title = {A Review of Standards for the Blue Economy -- Gaps \& Challenges}, url = {https://doi.org/10.5957/SMC-2022-061}, year = {2022}, bdsk-url-1 = {https://doi.org/10.5957/SMC-2022-061} } - Numerical modeling of moored floating platforms for wave energy converters using DualSPHysicsBonaventura Tagliafierro, Iván Martı́nez-Estévez, José M. Domı́nguez, Alejandro J. C. Crespo, Ryan G. Coe, Giorgio Bacelli, Moncho Gómez-Gesteira, and Giacomo ViccioneIn Proceedings of the ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering, Jun 2022V05AT06A016
The DualSPHysics open-source code establishes a comprehensive and efficient framework for simulating coastal and ocean engineering structures, which has been proven to be particularly reliable in wave energy converter (WEC) simulation. In this research, the experimental data of the floating oscillating surge wave energy converter (FOSWEC), is used for validation purposes. The FOSWEC2 device developed by SANDIA National Laboratories (US) is quite complex as it has several floating parts, anchor legs and a power take-off system (PTO) connected to the pitching motion of two flaps. Kinetic energy is in fact converted from the relative rotation between the flaps and a movable frame of the platform, setting a significant challenge for the validation of the FOSWEC with time-domain integrated methods. This work proposes a first validation campaign carried out using regular waves, and considering different parameters for the definition of the PTO system. The numerical model prediction for the platform motion (surge and pitch) and the relative flap pitch angle (bow and aft) shows that the model is able to deal with multi-body dynamics interacting with wave-induced forces.
@inproceedings{Tagliafierro:2022aa, address = {Hamburg, Germany}, author = {Tagliafierro, Bonaventura and Mart{\'\i}nez-Est{\'e}vez, Iv{\'a}n and Dom{\'\i}nguez, Jos{\'e} M. and Crespo, Alejandro J. C. and Coe, Ryan G. and Bacelli, Giorgio and G{\'o}mez-Gesteira, Moncho and Viccione, Giacomo}, bibtex_show = true, booktitle = {Proceedings of the ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering}, date-added = {2022-01-07 14:45:05 -0700}, date-modified = {2025-08-20 18:03:01 -0600}, doi = {10.1115/OMAE2022-78810}, eprint = {https://asmedigitalcollection.asme.org/OMAE/proceedings-pdf/OMAE2022/85895/V05AT06A016/6928960/v05at06a016-omae2022-78810.pdf}, month = jun, note = {V05AT06A016}, publisher = {ASME}, series = {International Conference on Offshore Mechanics and Arctic Engineering}, title = {Numerical modeling of moored floating platforms for wave energy converters using {DualSPHysics}}, url = {https://doi.org/10.1115/OMAE2022-78810}, volume = {Volume 5A: Ocean Engineering}, year = {2022}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2022-78810} } - Levelized avoided cost of energy analysis for wave energy: a case study in CaliforniaIn Proceedings of the ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering, Jun 2022V008T09A073
Wave energy converters have yet to reach broad market viability. Traditionally, levelized cost of energy has been considered the ultimate stage gate through which wave energy developers must pass in order to find success (i.e., the levelized cost of wave energy must be less than that of solar and wind). However, real world energy decisions are not based solely on levelized cost of energy. In this study, we consider the energy mix in California in the year 2045, upon which the state plans to achieve zero carbon energy production. By considering temporal electricity production and consumption, we are able to perform a more informed analysis of the decision process to address this challenge. The results show that, due to high level of ocean wave energy in the winter months, wave energy provides a valuable complement to solar and wind, which have higher production in the summer. Thus, based on this complementary temporal aspect, wave energy appears cost-effective, even when the cost of installation and maintenance is twice that of solar and wind.
@inproceedings{Coe:2022aa, address = {Hamburg, Germany}, author = {Coe, Ryan G. and Lavidas, George and Bacelli, Giorgio and Kobos, Peter H. and Neary, Vincent S.}, bibtex_show = true, booktitle = {Proceedings of the ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering}, date-added = {2022-01-07 14:26:27 -0700}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1115/OMAE2022-80731}, eprint = {https://asmedigitalcollection.asme.org/OMAE/proceedings-pdf/OMAE2022/85932/V008T09A073/6929644/v008t09a073-omae2022-80731.pdf}, month = jun, note = {V008T09A073}, publisher = {ASME}, series = {International Conference on Offshore Mechanics and Arctic Engineering}, title = {{Levelized avoided cost of energy analysis for wave energy: a case study in California}}, url = {https://doi.org/10.1115/OMAE2022-80731}, volume = {Volume 8: Ocean Renewable Energy}, year = {2022}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2022-80731} } - Self-tuning, load-mitigating feedback control of a 3-DOF point absorberDominic D. Forbush, Giorgio Bacelli, and Ryan G. CoeInternational Marine Energy Journal, Jun 2022
A simple, self-tuning multi-objective controller is demonstrated in simulation for a 3-DOF (surge, heave, pitch) point absorber. In previous work, the proposed control architecture has been shown to be effective in experiments for a variety of device archetypes for the single objective of the maximization of electrical power capture: here this architecture is extended to reduce device loading as well. In particular, PTO actuation forces and the minimization of fatigue damage (determined from the sum of wave-exerted and PTO forces) are considered as additional objectives for the self-tuning controller. Because the power surface is consistently fairly flat in the vicinity of control parameters that maximize power capture in contrasting sea-states (i.e., WECs are often broad banded), it is found to be generally possible to mitigate either fatigue damage or PTO load. However, PTO load is found to contradict with fatigue damage in some sea-states, limiting the efficacy of control objectives that attempt to mitigate both simultaneously. Additionally, coupling between the surge and pitch DOFs also limits the extent to which fatigue damage can be mitigated for both DOFs in some sea-states. Because control objectives can be considered a function of the sea-state (e.g., load mitigation may not be a concern until the sea is sufficiently large) a simple transition strategy is proposed and demonstrated. This transition strategy is found to be effective with some caveats: firstly, it cannot circumvent the aforementioned objective contradictions. Secondly, the thresholds at which objective transitions occur are somewhat exceeded: in this respect they cannot be considered as constraints and must be selected more conservatively. Finally, selection of well-performing transition parameters can be a function of sea-state. While a simple selection procedure is proposed, it is non-optimal, and a more robust selection procedure is suggested for future work.
@article{Forbush:2022ab, author = {Forbush, Dominic D. and Bacelli, Giorgio and Coe, Ryan G.}, bibtex_show = true, date-added = {2021-03-27 14:42:36 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.36688/imej.5.23-35}, journal = {International Marine Energy Journal}, month = jun, number = {1}, pages = {23-35}, title = {Self-tuning, load-mitigating feedback control of a {3-DOF} point absorber}, url = {https://marineenergyjournal.org/imej/article/view/68}, volume = {5}, year = {2022}, bdsk-url-1 = {https://marineenergyjournal.org/imej/article/view/68}, bdsk-url-2 = {https://doi.org/10.36688/imej.5.23-35} } - On limiting the influence of serial correlation in metocean data for prediction of extreme return levels and environmental contoursRyan G. Coe, Lance Manuel, and Andreas F. HaselsteinerOcean Engineering, Dec 2022
Metocean conditions change slowly, over the course of hours, sometimes even days, as storms develop and swells travel across the globe. Thus, measurements of these conditions are often serially correlated. However, many commonly employed methods for predicting metocean conditions for engineering design analyses are built upon an assumption of statistical independence of the data (e.g., hourly significant wave heights). In this brief study, we present an assessment of the serial (temporal) dependence in a selected metocean dataset. A method for processing a dataset that identifies and groups data sequences as “storm” events, and thus reduces serial dependence, is proposed and tested for estimating extreme metocean return levels. The results of this study show that the proposed procedure does indeed limit dependence and that environmental contours produced using this storm grouping procedure are reasonable based on the original dataset and when compared with associated alternative contours that ignore temporal dependence.
@article{Coe:2022ab, author = {Coe, Ryan G. and Manuel, Lance and Haselsteiner, Andreas F.}, bibtex_show = true, date-added = {2021-03-16 09:08:24 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1016/j.oceaneng.2022.113032}, issn = {0029-8018}, journal = {Ocean Engineering}, keywords = {Environmental contour, Metocean extremes, Joint distribution, Serial correlation, Storms}, month = dec, pages = {113032}, title = {On limiting the influence of serial correlation in metocean data for prediction of extreme return levels and environmental contours}, url = {https://www.sciencedirect.com/science/article/pii/S0029801822023150}, volume = {266}, year = {2022}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S0029801822023150}, bdsk-url-2 = {https://doi.org/10.1016/j.oceaneng.2022.113032} } - A comparison of efficiency-aware model-predictive control approaches for wave energy devicesJournal of Ocean Engineering and Marine Energy, Feb 2022
This paper compares four different formulations of model predictive control that attempt to maximise electrical power generated by a wave energy converter (WEC). Control laws include (1) pure maximisation of mechanical power, (2) maximisation of mechanical power with a control penalty factor, (3) maximisation of electrical power using power conversion efficiency, and (4) maximisation of electrical power using the full electro-mechanical model of a system. For this study, a wave-to-wire model is developed for a floating spherical buoy connected to a permanent magnet synchronous generator. The performance of the controllers, including the mechanical and electrical power outputs, is compared in irregular wave conditions for the unconstrained and force-constrained scenarios. The results demonstrate that the controller designed to maximise mechanical power is not suitable for practical applications and may lead to negative electrical power output due to the non-ideal power take-off efficiency. Moreover, the replacement of the power take-off dynamics by the efficiency coefficient does not guarantee the maximum electrical power production.
@article{Sergiienko:2022aa, author = {Sergiienko, Nataliia Y. and Bacelli, Giorgio and Coe, Ryan G. and Cazzolato, Benjamin S.}, bibtex_show = true, date-added = {2021-03-16 09:04:55 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1007/s40722-021-00214-x}, id = {Sergiienko2021}, isbn = {2198-6452}, journal = {Journal of Ocean Engineering and Marine Energy}, month = feb, pages = {17-29}, title = {A comparison of efficiency-aware model-predictive control approaches for wave energy devices}, url = {https://doi.org/10.1007/s40722-021-00214-x}, volume = {8}, year = {2022}, bdsk-url-1 = {https://doi.org/10.1007/s40722-021-00214-x} } - Development and characterization of a coupled structural dynamics model for the Sandia wave energy converter testbedLiliana Haus, D. Todd Griffith, Ryan G. Coe, and Giorgio BacelliJournal of Ocean Engineering and Marine Energy, Jan 2022
Validated design tools are one of the key needs for achieving market-competitive levelized cost of energy for wave energy converters (WECs). Sandia National Laboratories recently completed model-scale wave tank tests in the US Navy’s Maneuvering and Sea Keeping (MASK) basin with a point absorber-style WEC. In these tests, the WEC was mounted to the MASK Basin bridge for ease of access and to facilitate thorough investigation of WEC dynamics modelling and control design. In collaboration with Sandia, the University of Texas at Dallas developed coupled models of the dynamics of the Sandia WEC and MASK Basin bridge. Initial modelling efforts focused on developing a simple, but accurate model of the MASK Basin bridge that agrees well with measured modes of vibration and measured static displacement under loading. A coupled dynamics model of the Sandia WEC with the validated bridge model was also developed. This coupled model has been examined to determine the degree of coupling between the dynamic responses of the bridge and WEC. Further, the coupled model is useful in the design of future, safe and well-designed experiments. Additionally, the process of including structural models when considering WEC dynamics and control will become increasingly important for larger scale devices. In this paper, first, the creation and calibration of a simple finite element model of the MASK Basin bridge is described. Next, a spring–mass–damper-inspired WEC model is coupled to the bridge model and the resulting coupled model is mathematically verified and validated against experimental data. Finally, the degree of coupling between the WEC and bridge is quantified, a reduced order model is developed, and linearity of the relationship between the wave input and coupled system output is analyzed.
@article{Haus:2022aa, author = {Haus, Liliana and Griffith, D. Todd and Coe, Ryan G. and Bacelli, Giorgio}, bibtex_show = true, date-added = {2020-12-25 13:35:18 -0700}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1007/s40722-021-00220-z}, isbn = {2198-6452}, journal = {Journal of Ocean Engineering and Marine Energy}, month = jan, pages = {117-135}, title = {Development and characterization of a coupled structural dynamics model for the {Sandia} wave energy converter testbed}, url = {https://doi.org/10.1007/s40722-021-00220-z}, volume = {8}, year = {2022}, bdsk-url-1 = {https://doi.org/10.1007/s40722-021-00220-z} } - A Self-Tuning WEC Controller For Changing Sea StatesDominic D. Forbush, Giorgio Bacelli, Steven J. Spencer, Ryan G. Coe, David G. Wilson, and Bryson RobertsonInternational Marine Energy Journal, Dec 2022
A self-tuning proportional-integral control law prescribing motor torques was tested in experiment on a three degree-of-freedom wave energy converter. The control objective was to maximize electrical power. The control law relied upon an identified model of device intrinsic impedance to generate a frequency-domain estimate of the wave-induced excitation force and measurements of device velocities. The control law was tested in irregular sea-states that evolved over hours (a rapid, but realistic time-scale) and that changed instantly (an unrealistic scenario to evaluate controller response). For both cases, the controller converges to gains that closely approximate the postcalculated optimal gains for all degrees of freedom in a sufficiently short-time for realistic sea states. In addition, electrical power was found to be relatively insensitive to gain tuning over a broad range of gains, implying that an imperfectly tuned controller does not result in a large penalty to electrical power capture. Because the controller relies on an identified model of device intrinsic impedance, the sensitivity of power capture was evaluated with respect to uncertainty in the constituent terms of intrinsic impedance. Power capture is found to be relatively insensitive to uncertainty of 20% in constituent terms of the identified intrinsic impedance model. An extension of this control law that allows for adaptation to a changing device impedance model over time is proposed for long-term deployments, as well as an approach to explicitly handle constraints within this architecture.
@article{Forbush:2022ac, author = {Forbush, Dominic D. and Bacelli, Giorgio and Spencer, Steven J. and Coe, Ryan G. and Wilson, David G. and Robertson, Bryson}, bibtex_show = true, date-added = {2020-10-20 13:56:34 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.36688/imej.5.327-338}, journal = {International Marine Energy Journal}, month = dec, number = {3}, pages = {327--338}, title = {A Self-Tuning {WEC} Controller For Changing Sea States}, url = {https://marineenergyjournal.org/imej/article/view/70}, volume = {5}, year = {2022}, bdsk-url-1 = {https://marineenergyjournal.org/imej/article/view/70}, bdsk-url-2 = {https://doi.org/10.36688/imej.5.327-338} } - Design and testing of a free floating dual flap wave energy converterEnergy, Feb 2022
With a wide variety of wave energy device archetypes currently under consideration, it is a major challenge to ensure that research findings and methods are broadly applicable. In particular, the design and testing of wave energy control systems, a process which includes experimental design, empirical modeling, control design, and performance evaluation, is of interest. This goal motivated the redesign and testing of a floating dual flap wave energy converter. As summarized in this paper, the steps taken in the design, testing, and analysis of the device mirrored those previously demonstrated on a three-degree of freedom point absorber device. The method proposed does not require locking WEC degrees of freedom to develop an excitation model, and presents a more attainable system identification procedure for at-sea deployments. The results show that the methods employed work well for this dual flap device, lending additional support for the broad applicability of the design and testing methods applied here. The aim of this paper is to demonstrate that these models are particularly useful for deducing areas of device design or controller implementation that can be reasonably improved to increase device power capture.
@article{Forbush:2022aa, author = {Forbush, Dominic D. and Bacelli, Giorgio and Spencer, Steven J. and Coe, Ryan G. and Bosma, Bret and Lomonaco, Pedro}, bibtex_show = true, date = {2020}, date-added = {2020-10-07 12:35:17 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1016/j.energy.2021.122485}, groups = {AdvWecCntrls Pubs}, issn = {0360-5442}, journal = {Energy}, keywords = {Wave energy, Feedback control, System identification, Frequency domain}, month = feb, pages = {122485}, title = {Design and testing of a free floating dual flap wave energy converter}, url = {https://www.sciencedirect.com/science/article/pii/S0360544221027341}, volume = {240}, year = {2022}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S0360544221027341}, bdsk-url-2 = {https://doi.org/10.1016/j.energy.2021.122485} }
2021
- The Marine and Hydrokinetic ToolKit (MHKiT) for Data Quality Control and AnalysisSterling Olson, Rebecca Fao, Ryan Coe, Kelley Ruehl, Frederick Driscoll, Budi Gunawan, Chitra Sivaraman, Carina Lansing, and Hristo IvanovIn Proceedings of the 14th European Wave and Tidal Energy Conference (EWTEC2021), Sep 2021
The ability to handle data is critical at all stages of marine energy (ME) development. The marine hydrokinetic toolkit (MHKiT) is an open-source marine energy software, which includes modules for ingesting, applying quality control, processing, visualizing, and managing data. MHKiT-Python and MHKiT-MATLAB provide robust and verified functions that are needed by the ME community to standardize data processing. Calculations and visualizations adhere to International Electrotechnical Commission (IEC) technical specifications and other guidelines. A resource assessment of NDBC buoy 46050 near PACWAVE is performed using MHKiT and discusses comparisons to the resource assessment provided performed by Dunkel et al.
@inproceedings{Olson:2021aa, address = {Pymouth, UK}, author = {Olson, Sterling and Fao, Rebecca and Coe, Ryan and Ruehl, Kelley and Driscoll, Frederick and Gunawan, Budi and Sivaraman, Chitra and Lansing, Carina and Ivanov, Hristo}, bibtex_show = true, booktitle = {Proceedings of the 14th European Wave and Tidal Energy Conference (EWTEC2021)}, date-added = {2021-09-28 08:54:44 -0600}, date-modified = {2025-08-20 10:45:09 -0600}, month = sep, title = {{The Marine and Hydrokinetic ToolKit (MHKiT) for Data Quality Control and Analysis}}, url = {https://www.osti.gov/biblio/1827627}, year = {2021}, bdsk-url-1 = {https://www.osti.gov/biblio/1827627} } - A second benchmarking exercise on estimating extreme environmental conditionsAndreas F. Haselsteiner, Ryan G. Coe, and Lance ManuelOcean Engineering, Sep 2021
Estimating extreme environmental conditions remains a key challenge in the design of offshore structures. This paper describes an exercise for benchmarking methods for extreme environmental conditions, which follows on from an initial benchmarking exercise introduced at OMAE 2019. In this second exercise, we address the problem of estimating extreme metocean conditions in a variable and changing climate. The study makes use of several very long datasets from a global climate model, including a 165-year historical run, a 700-year pre-industrial control run, which represents a quasi-steady state climate, and several runs under various future emissions scenarios. The availability of the long datasets allows for an in-depth analysis of the uncertainties in the estimated extreme conditions and an attribution of the relative importance of uncertainties resulting from modelling choices, natural climate variability, and potential future changes to the climate. This paper outlines the methodology for the second collaborative benchmarking exercise as well as presenting baseline results for the selected datasets.
@article{Haselsteiner:2021aa, author = {Haselsteiner, Andreas F. and Coe, Ryan G. and Manuel, Lance}, bibtex_show = true, date-added = {2021-05-18 09:59:30 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1016/j.oceaneng.2021.109111}, issn = {0029-8018}, journal = {Ocean Engineering}, pages = {109111}, title = {A second benchmarking exercise on estimating extreme environmental conditions}, url = {https://www.sciencedirect.com/science/article/pii/S0029801821005473}, year = {2021}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S0029801821005473}, bdsk-url-2 = {https://doi.org/10.1016/j.oceaneng.2021.109111} } - A second benchmarking exercise on estimating extreme environmental conditions: methodology & baseline resultsIn Proceedings of the ASME 2021 40th International Conference on Ocean, Offshore and Arctic Engineering (OMAE2021), Jun 2021V002T02A015
Estimating extreme environmental conditions remains a key challenge in the design of offshore structures. This paper describes an exercise for benchmarking methods for extreme environmental conditions, which follows on from an initial benchmarking exercise introduced at OMAE 2019. In this second exercise, we address the problem of estimating extreme metocean conditions in a variable and changing climate. The study makes use of several very long datasets from a global climate model, including a 165-year historical run, a 700-year pre-industrial control run, which represents a quasi-steady state climate, and several runs under various future emissions scenarios. The availability of the long datasets allows for an in-depth analysis of the uncertainties in the estimated extreme conditions and an attribution of the relative importance of uncertainties resulting from modelling choices, natural climate variability, and potential future changes to the climate. This paper outlines the methodology for the second collaborative benchmarking exercise as well as presenting baseline results for the selected datasets.
@inproceedings{Mackay:2021aa, address = {Virtual, Online}, author = {Mackay, Ed and Haselsteiner, Andreas F. and Coe, Ryan G. and Manuel, Lance}, bibtex_show = true, booktitle = {Proceedings of the ASME 2021 40th International Conference on Ocean, Offshore and Arctic Engineering (OMAE2021)}, date-added = {2020-12-05 13:40:42 -0700}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1115/OMAE2021-64874}, eprint = {https://asmedigitalcollection.asme.org/OMAE/proceedings-pdf/OMAE2021/85123/V002T02A015/6769024/v002t02a015-omae2021-64874.pdf}, month = jun, note = {V002T02A015}, series = {International Conference on Offshore Mechanics and Arctic Engineering}, title = {A second benchmarking exercise on estimating extreme environmental conditions: methodology \& baseline results}, url = {https://doi.org/10.1115/OMAE2021-64874}, volume = {Volume 2: Structures, Safety, and Reliability}, year = {2021}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2021-64874} } - Scoping and concept design of a WEC for autonomous powerIn OCEANS 2021: San Diego – Porto, Sep 2021
This paper reports results from an ongoing investigation on potential ways to utilize small wave energy devices that can be transported in, and deployed from, torpedo tubes. The devices are designed to perform designated ocean measurement operations and thus need to convert enough energy to power onboard sensors, while storing any excess energy to support vehicle recharging operations. Examined in this paper is a traditional tubular oscillating water column device, and particular interest here is in designs that lead to optimization of power converted from shorter wind sea waves. A two step design procedure is investigated here, wherein a more approximate two-degree-of-freedom model is first used to identify relative dimensions (of device elements) that optimize power conversion from relative oscillations between the device elements. A more rigorous mathematical model based on the hydrodynamics of oscillating pressure distributions within solid oscillators is then used to provide the hydrodynamic coefficients, forces, and flow rates for the device. These results provide a quick but rigorous way to estimate the energy conversion performance of the device in various wave climates, while enabling more accurate design of the power takeoff and energy storage systems.
@inproceedings{Korde:2021aa, address = {San Diego, CA}, author = {Korde, Umesh A. and Gish, L. Andrew and Bacelli, Giorgio and Coe, Ryan G.}, bibtex_show = true, booktitle = {OCEANS 2021: {San Diego} -- {Porto}}, date-added = {2020-11-11 14:25:19 -0700}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.23919/OCEANS44145.2021.9705660}, month = sep, pages = {1-6}, title = {Scoping and concept design of a {WEC} for autonomous power}, url = {https://ieeexplore.ieee.org/document/9705660}, year = {2021}, bdsk-url-1 = {https://ieeexplore.ieee.org/document/9705660}, bdsk-url-2 = {https://doi.org/10.23919/OCEANS44145.2021.9705660} } - Modeling and predicting power from a WEC arrayRyan G. Coe, Giorgio Bacelli, Daniel Gaebele, Alfred Cotten, Cameron McNattand David G. Wilson, Wayne Weaver, Jeremy L. Casper, Mohammad Khalil, and Ann R. DallmanIn OCEANS 2021: San Diego – Porto, Sep 2021
This study presents a numerical model of a WEC array. The model will be used in subsequent work to study the ability of data assimilation to support power prediction from WEC arrays and WEC array design. In this study, we focus on design, modeling, and control of the WEC array. A case study is performed for a small remote Alaskan town. Using an efficient method for modeling the linear interactions within a homogeneous array, we produce a model and predictionless feedback controllers for the devices within the array. The model is applied to study the effects of spectral wave forecast errors on power output. The results of this analysis show that the power performance of the WEC array will be most strongly affected by errors in prediction of the spectral period, but that reductions in performance can realistically be limited to less than 10% based on typical data assimilation based spectral forecasting accuracy levels.
@inproceedings{Coe:2021ac, address = {San Diego, CA}, author = {Coe, Ryan G. and Bacelli, Giorgio and Gaebele, Daniel and Cotten, Alfred and Wilson, Cameron McNattand David G. and Weaver, Wayne and Casper, Jeremy L. and Khalil, Mohammad and Dallman, Ann R.}, bibtex_show = true, booktitle = {OCEANS 2021: San Diego -- Porto}, date-added = {2020-11-11 13:12:27 -0700}, date-modified = {2025-10-02 07:49:14 -0600}, doi = {10.23919/OCEANS44145.2021.9706128}, month = sep, pages = {1-10}, title = {Modeling and predicting power from a {WEC} array}, url = {https://ieeexplore.ieee.org/abstract/document/9706128}, year = {2021}, bdsk-url-1 = {https://ieeexplore.ieee.org/abstract/document/9706128}, bdsk-url-2 = {https://doi.org/10.23919/OCEANS44145.2021.9706128} } - Modelling a Heaving Point-Absorber with a Closed-Loop Control System Using the DualSPHysics CodePablo Ropero-Giralda, Alejandro J. C. Crespo, Ryan G. Coe, Bonaventura Tagliafierro, Jose M. Dominguez, Giorgio Bacelli, and Moncho Gomez-GesteiraEnergies, Sep 2021
The present work addresses the need for an efficient, versatile, accurate and open-source numerical tool to be used during the design stage of wave energy converters (WECs). The device considered here is the heaving point-absorber developed and tested by Sandia National Laboratories. The smoothed particle hydrodynamics (SPH) method, as implemented in DualSPHysics, is proposed since its meshless approach presents some important advantages when simulating floating devices. The dynamics of the power take-off system are also modelled by coupling DualSPHysics with the multi-physics library Project Chrono. A satisfactory matching between experimental and numerical results is obtained for: (i) the heave response of the device when forced via its actuator; (ii) the vertical forces acting on the fixed device under regular waves and; (iii) the heave response of the WEC under the action of both regular waves and the actuator force. This proves the ability of the numerical approach proposed to simulate accurately the fluid–structure interaction along with the WEC’s closed-loop control system. In addition, radiation models built from the experimental and WAMIT results are compared with DualSPHysics by plotting the intrinsic impedance in the frequency domain, showing that the SPH method can be also employed for system identification.
@article{Ropero-Giralda:2021aa, article-number = {760}, author = {Ropero-Giralda, Pablo and Crespo, Alejandro J. C. and Coe, Ryan G. and Tagliafierro, Bonaventura and Dominguez, Jose M. and Bacelli, Giorgio and Gomez-Gesteira, Moncho}, bibtex_show = true, date-added = {2020-10-28 13:55:17 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.3390/en14030760}, issn = {1996-1073}, journal = {Energies}, number = {3}, title = {Modelling a Heaving Point-Absorber with a Closed-Loop Control System Using the {DualSPHysics} Code}, url = {https://www.mdpi.com/1996-1073/14/3/760}, volume = {14}, year = {2021}, bdsk-url-1 = {https://www.mdpi.com/1996-1073/14/3/760}, bdsk-url-2 = {https://doi.org/10.3390/en14030760} } - Design Load Case Generator: Web App Tool to Determine IEC 62600-2 Standard Design Load RequirementsVincent S. Neary, Andreas F. Haselsteiner, Rachel An, Lena Stroer, KL Windmeier, Soengho Ahn, and Ryan G. CoeIn Proceedings of the 14th European Wave and Tidal Energy Conference (EWTEC2021), Sep 2021
@inproceedings{Neary:2021aa, address = {Plymouth, UK}, author = {Neary, Vincent S. and Haselsteiner, Andreas F. and An, Rachel and Stroer, Lena and Windmeier, KL and Ahn, Soengho and Coe, Ryan G.}, bibtex_show = true, booktitle = {Proceedings of the 14th European Wave and Tidal Energy Conference (EWTEC2021)}, date-added = {2020-10-20 10:59:16 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, month = sep, title = {{Design Load Case Generator:} {Web App Tool} to Determine {IEC 62600-2} Standard Design Load Requirements}, year = {2021} } - DualSPHysics: a numerical tool to design point-absorbing WECsPablo Ropero-Giralda, Alejandro J. C. Crespo, Ryan G. Coe, Bonaventura Tagliafierro, Jose M. Dominguez, Giorgio Bacelli, and Moncho Gomez-GesteiraIn Proceedings of the 14th European Wave and Tidal Energy Conference (EWTEC2021), Sep 2021
DualSPHysics has been employed to simulate the three main experiments conducted during the design stage of a wave energy converter (WEC): a radiation test, a diffraction test, and a dynamic response test. In the radiation test, the numerical heave motion of the device for a monochromatic multisine force signal was validated against experimental data, where a broad spectrumpoly-chromatic signal was used to build an impedance model via system identification. The model allowed obtaining key hydrodynamic parameters of the point-absorber, such as the added mass and the radiation damping. The numerical results obtained were compared with experiments and with output from the linear potential solver WAMIT[1]. During the diffraction test, the device was completely locked and subjected to incoming waves; the forces exerted on the WEC by regular waves were measured and compared with the experimental ones. Finally, the dynamic response test includes both waves and forcing from the power take-off(PTO)system. The dynamic response of a closed-loop system ,in which the applied PTO force depends on the position and velocity of the device at each time instant. For all these tests, DualSPHysics proves to be capable of being used in the design of WECs.
@inproceedings{Ropero-Giralda:2021ab, address = {Plymouth, UK}, author = {Ropero-Giralda, Pablo and Crespo, Alejandro J. C. and Coe, Ryan G. and Tagliafierro, Bonaventura and Dominguez, Jose M. and Bacelli, Giorgio and Gomez-Gesteira, Moncho}, bibtex_show = true, booktitle = {Proceedings of the 14th European Wave and Tidal Energy Conference (EWTEC2021)}, date-added = {2020-10-15 14:12:48 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, month = sep, title = {{DualSPHysics:} a numerical tool to design point-absorbing {WECs}}, year = {2021} } - Maybe less is more: Considering capacity factor, saturation, variability, and filtering effects of wave energy devicesApplied Energy, Sep 2021
While a great deal of research has been performed to quantify and characterize the wave energy resource, there are still open questions about how a wave energy developer should use this wave resource information to design a wave energy converter device to suit a specific environment or, alternatively, to assess potential deployment locations. It is natural to focus first on the impressive magnitudes of power available from ocean waves, and to be drawn to locations where mean power levels are highest. However, a number of additional factors such as intermittency and capacity factor may be influential in determining economic viability of a wave energy converter, and should therefore be considered at the resource level, so that these factors can influence device design decisions. This study examines a set of wave resource metrics aimed towards this end of bettering accounting for variability in wave energy converter design. The results show distinct regional trends that may factor into project siting and wave energy converter design. Although a definitive solution for the optimal size of a wave energy converter is beyond the reaches of this study, the evidence presented does support the idea that smaller devices with lower power ratings may merit closer consideration.
@article{Coe:2021aa, author = {Coe, Ryan G. and Ahn, Seongho and Neary, Vincent S. and Kobos, Peter H. and Bacelli, Giorgio}, bibtex_show = true, date-added = {2020-10-15 13:13:23 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1016/j.apenergy.2021.116763}, issn = {0306-2619}, journal = {Applied Energy}, keywords = {Wave energy converter (WEC), Wave power resource, Practical resource}, pages = {116763}, title = {Maybe less is more: Considering capacity factor, saturation, variability, and filtering effects of wave energy devices}, url = {https://www.sciencedirect.com/science/article/pii/S0306261921002701}, volume = {291}, year = {2021}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S0306261921002701}, bdsk-url-2 = {https://doi.org/10.1016/j.apenergy.2021.116763} } - The MBARI-WEC: a power source for ocean sensingJournal of Ocean Engineering and Marine Energy, Sep 2021
Interest in wave energy converters to provide autonomous power to various ocean-bound systems, such as autonomous underwater vehicles, sensor systems, and even aquaculture farms, has grown in recent years. The Monterey Bay Aquarium Research Institute has developed and deployed a small two-body point absorber wave energy device suitable to such needs. This paper provides a description of the system to support future open-source access to the device and further the general development of similar wave energy systems. Additionally, to support future control design and system modification efforts, a set of hydrodynamic models are presented and cross-compared. To test the viability of using a linear frequency-domain admittance model for controller tuning, the linear model is compared against four WEC-Sim models of increasing complexity. The linear frequency-domain model is found to be generally adequate for capturing system dynamics, as the model agreement is good and the degree of nonlinearity introduced in the WEC-Sim models is generally less than 2.5%.
@article{Hamilton:2021aa, author = {Hamilton, Andrew and Cazenave, Fran\c{c}ois and Forbush, Dominic and Coe, Ryan G. and Bacelli, Giorgio}, bibtex_show = true, da = {2021/05/01}, date-added = {2020-10-15 13:02:28 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1007/s40722-021-00197-9}, id = {Hamilton2021}, isbn = {2198-6452}, journal = {Journal of Ocean Engineering and Marine Energy}, number = {2}, pages = {189--200}, title = {The {MBARI-WEC}: a power source for ocean sensing}, ty = {JOUR}, url = {https://doi.org/10.1007/s40722-021-00197-9}, volume = {7}, year = {2021}, bdsk-url-1 = {https://doi.org/10.1007/s40722-021-00197-9} } - A benchmarking exercise for environmental contoursAndreas F. Haselsteiner, Ryan G. Coe, Lance Manuel, Wei Chai, Bernt Leira, Guilherme Clarindo, C. Guedes Soares, Hannesdóttir, Nikolay Dimitrov, Aljoscha Sander, Jan-Hendrik Ohlendorf, Klaus-Dieter Thoben, Guillaume Hauteclocque, Ed Mackay, Philip Jonathan, Chi Qiao, Andrew Myers, Anna Rode, Arndt Hildebrandt, Boso Schmidt, Erik Vanem, and Arne Bang HusebyOcean Engineering, Sep 2021
Environmental contours are used to simplify the process of design response analysis. A wide variety of contour methods exist; however, there have been a very limited number of comparisons of these methods to date. This paper is the output of an open benchmarking exercise, in which contributors developed contours based on their preferred methods and submitted them for a blind comparison study. The exercise had two components—one, focusing on the robustness of contour methods across different offshore sites and, the other, focusing on characterizing sampling uncertainty. Nine teams of researchers contributed to the benchmark. The analysis of the submitted contours highlighted significant differences between contours derived via different methods. For example, the highest wave height value along a contour varied by as much as a factor of two between some submissions while the number of metocean data points or observations that fell outside a contour deviated by an order of magnitude between the contributions (even for contours with a return period shorter than the duration of the record). These differences arose from both different joint distribution models and different contour construction methods, however, variability from joint distribution models appeared to be higher than variability from contour construction methods.
@article{Haselsteiner:2021ab, author = {Haselsteiner, Andreas F. and Coe, Ryan G. and Manuel, Lance and Chai, Wei and Leira, Bernt and Clarindo, Guilherme and {Guedes Soares}, C. and {\'A}sta Hannesd{\'o}ttir and Dimitrov, Nikolay and Sander, Aljoscha and Ohlendorf, Jan-Hendrik and Thoben, Klaus-Dieter and de Hauteclocque, Guillaume and Mackay, Ed and Jonathan, Philip and Qiao, Chi and Myers, Andrew and Rode, Anna and Hildebrandt, Arndt and Schmidt, Boso and Vanem, Erik and Huseby, Arne Bang}, bibtex_show = true, date-added = {2020-10-15 13:00:54 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1016/j.oceaneng.2021.109504}, issn = {0029-8018}, journal = {Ocean Engineering}, keywords = {Environmental contour, Metocean extremes, Joint distribution, Extreme response, Structural reliability}, pages = {109504}, title = {A benchmarking exercise for environmental contours}, url = {https://www.sciencedirect.com/science/article/pii/S0029801821009033}, volume = {236}, year = {2021}, bdsk-url-1 = {https://github.com/ec-benchmark-organizers/ec-benchmark/blob/master/publications/2021-01-19_EC_Benchmark_Joint_Paper_WithFrontPages.pdf}, bdsk-url-2 = {https://tinyurl.com/2ubs935k} } - Development of a comparison framework for evaluating environmental contours of extreme sea statesAubrey Eckert, Nevin Martin, Ryan G. Coe, Bibiana Seng, Zacharia Stuart, and Zachary MorrellJournal of Marine Science and Engineering, Sep 2021
Environmental contours of extreme sea states are often utilized for the purposes of reliability-based offshore design. Many methods have been proposed to estimate environmental contours of extreme sea states, including, but not limited to, the traditional inverse first-order reliability method (I-FORM) and subsequent modifications, copula methods, and Monte Carlo methods. These methods differ in terms of both the methodology selected for defining the joint distribution of sea state parameters and in the method used to construct the environmental contour from the joint distribution. It is often difficult to compare the results of proposed methods to determine which method should be used for a particular application or geographical region. The comparison of the predictions from various contour methods at a single site and across many sites is important to making environmental contours of extreme sea states useful in practice. The goal of this paper is to develop a comparison framework for evaluating methods for developing environmental contours of extreme sea states. This paper develops generalized metrics for comparing the performance of contour methods to one another across a collection of study sites, and applies these metrics and methods to develop conclusions about trends in the wave resource across geographic locations, as demonstrated for a pilot dataset. These proposed metrics and methods are intended to judge the environmental contours themselves relative to other contour methods, and are thus agnostic to a specific device, structure, or field of application. The metrics developed and applied in this paper include measures of predictive accuracy, physical validity, and aggregated temporal performance that can be used to both assess contour methods and provide recommendations for the use of certain methods in various geographical regions. The application and aggregation of the metrics proposed in this paper outline a comparison framework for environmental contour methods that can be applied to support design analysis workflows for offshore structures. This comparison framework could be extended in future work to include additional metrics of interest, potentially including those to address issues pertinent to a specific application area or analysis discipline, such as metrics related to structural response across contour methods or additional physics-based metrics based on wave dynamics.
@article{Eckert:2021aa, author = {Eckert, Aubrey and Martin, Nevin and Coe, Ryan G. and Seng, Bibiana and Stuart, Zacharia and Morrell, Zachary}, bibtex_show = true, date-added = {2020-10-15 12:58:26 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.3390/jmse9010016}, journal = {Journal of Marine Science and Engineering}, number = {1}, pages = {16}, title = {Development of a comparison framework for evaluating environmental contours of extreme sea states}, url = {https://doi.org/10.3390/jmse9010016}, volume = {9}, year = {2021}, bdsk-url-1 = {https://doi.org/10.3390/jmse9010016} } - Comments on control of wave energy convertersGiorgio Bacelli, and Ryan G. CoeIEEE Transactions on Control Systems Technology, Jan 2021
The main objective of this letter is to consolidate the knowledge about the dynamics and control of oscillating-body wave energy converters (WECs). A number of studies have shown that control systems strongly affect power absorption; however, there remains a need for a concise and integrated explanation of the theoretical and practical implications that control can have on both performance and the broader WEC design process. This short letter attempts to fill this gap by presenting a discussion on the key practical aspects concerning the dynamics and control of oscillating-body WEC. In particular, the focus is on the choice of control models and a simple causal control scheme suitable for real-time implementation. Finally, consideration is given to the effect of the power takeoff (PTO) on the maximization of electrical power, thus leading to the derivation of useful conditions for the control co-design of the PTO system.
@article{Bacelli:2021aa, author = {Bacelli, Giorgio and Coe, Ryan G.}, bibtex_show = true, date-added = {2020-10-07 12:37:21 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1109/TCST.2020.2965916}, groups = {AdvWecCntrls Pubs}, journal = {IEEE Transactions on Control Systems Technology}, keywords = {Impedance;Frequency control;Control systems;Force;Absorption;Biological system modeling;Impedance matching;Control co-design;impedance matching;wave energy converter (WEC)}, month = jan, number = {1}, pages = {478-481}, title = {Comments on control of wave energy converters}, url = {https://ieeexplore.ieee.org/document/9005201}, volume = {29}, year = {2021}, bdsk-url-1 = {https://ieeexplore.ieee.org/document/9005201}, bdsk-url-2 = {https://doi.org/10.1109/TCST.2020.2965916} } - A practical approach to wave energy modeling and controlRyan G. Coe, Giorgio Bacelli, and Dominic ForbushRenewable and Sustainable Energy Reviews, Jan 2021
The potential for control design to dramatically improve the economic viability of wave energy has generated a great deal of interest and excitement. However, for a number of reasons, the promised benefits from better control designs have yet to be widely realized by wave energy devices and wave energy remains a relatively nascent technology. This brief paper summarizes a simple, yet powerful approach to wave energy dynamics modeling, and subsequent control design based on impedance matching. Our approach leverages the same concepts that are exploited by a simple FM radio to achieve a feedback controller for wave energy devices that approaches optimal power absorption. If fully utilized, this approach can deliver immediate and consequential reductions to the cost of wave energy. Additionally, this approach provides the necessary framework for control co-design of a wave energy converter, in which an understanding of the control logic allows for synchronous design of the device control system and hardware.
@article{Coe:2021ab, author = {Coe, Ryan G. and Bacelli, Giorgio and Forbush, Dominic}, bibtex_show = true, date-added = {2020-10-07 12:35:05 -0600}, date-modified = {2025-08-20 17:35:16 -0600}, doi = {10.1016/j.rser.2021.110791}, issn = {1364-0321}, journal = {Renewable and Sustainable Energy Reviews}, keywords = {Wave energy converter (WEC), Impedance matching, Control, Marine renewable energy, Power maximization}, pages = {110791}, title = {{A practical approach to wave energy modeling and control}}, url = {https://www.sciencedirect.com/science/article/pii/S1364032121000861}, volume = {142}, year = {2021}, bdsk-url-1 = {https://www.techrxiv.org/articles/preprint/A_practical_approach_to_wave_energy_modeling_and_control/12939488}, bdsk-url-2 = {https://doi.org/10.36227/techrxiv.12939488.v1}, bdsk-url-3 = {https://www.sciencedirect.com/science/article/pii/S1364032121000861}, bdsk-url-4 = {https://doi.org/10.1016/j.rser.2021.110791} }
2020
- Super Capacitor Energy Storage System Design for Wave Energy Converter DemonstrationWayne W. Weaver, David G. Wilson, Alex Hagmuller, Max Ginsburg, Giorgio Bacelli, Rush D. Robinett, Ryan Coe, and Budi GunawanIn 2020 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM), Jun 2020
Aquaharmonics Inc (AH) intends to develop, build, and perform open ocean testing on a 1:7 scale device. Testing will include data capture and performance optimization in wave climates representative of full scale in potential deployment locations. Test data will be used to develop a scaled device to provide minimized levelized cost of energy (LCOE) for markets with high power demand.
@inproceedings{Weaver:2020aa, address = {Sorrento, Italy}, author = {Weaver, Wayne W. and Wilson, David G. and Hagmuller, Alex and Ginsburg, Max and Bacelli, Giorgio and Robinett, Rush D. and Coe, Ryan and Gunawan, Budi}, bibtex_show = true, booktitle = {2020 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)}, date-added = {2021-01-16 08:37:58 -0700}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1109/SPEEDAM48782.2020.9161965}, keywords = {demand side management;power markets;supercapacitors;wave power generation;high power demand;LCOE;levelized cost of energy;scaled device;deployment locations;wave climates representative;performance optimization;data capture;open ocean testing;aquaharmonics Inc;wave energy converter demonstration;super capacitor energy storage system design;Inverters;Testing;Integrated circuit modeling;Data models;Resistance;Performance evaluation;Capacitance}, month = jun, pages = {564-570}, publisher = {IEEE}, title = {Super Capacitor Energy Storage System Design for Wave Energy Converter Demonstration}, url = {https://doi.org/10.1109/SPEEDAM48782.2020.9161965}, year = {2020}, bdsk-url-1 = {https://doi.org/10.1109/SPEEDAM48782.2020.9161965} } - Deterministic Incident Wave Elevation Prediction in Intermediate Water DepthUmesh A. Korde, Ryan G. Coe, and Giorgio BacelliJournal of Ocean Engineering and Marine Energy, Nov 2020
Potential performance gains from optimal (non-causal) impedance-matching control of wave energy devices in irregular ocean waves are dependent on deterministic wave elevation prediction techniques that work well in practical applications. Although a number of devices are designed for operation in intermediate water depths, little work has been reported on deterministic wave prediction in such depths. Investigated in this paper is a deterministic wave-prediction technique based on an approximate propagation model that leads to an analytical formulation, which may be convenient to implement in practice. To improve accuracy, an approach to combine predictions based on multiple up-wave measurement points is evaluated. The overall method is tested using experimental time-series measurements recorded in the U.S. Navy MASK basin in Carderock, MD, USA. For comparison, an alternative prediction approach based on Fourier coefficients is also tested with the same data. Comparison of prediction approaches with direct measurements suggest room for improvement. Possible sources of error including tank reflections are estimated, and potential mitigation approaches are discussed.
@article{Korde:2020aa, author = {Korde, Umesh A. and Coe, Ryan G. and Bacelli, Giorgio}, bibtex_show = true, da = {2020/11/06}, date-added = {2020-10-15 13:12:29 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1007/s40722-020-00177-5}, id = {Korde2020}, isbn = {2198-6452}, journal = {Journal of Ocean Engineering and Marine Energy}, month = nov, number = {4}, pages = {359--376}, title = {Deterministic Incident Wave Elevation Prediction in Intermediate Water Depth}, ty = {JOUR}, url = {https://doi.org/10.1007/s40722-020-00177-5}, volume = {6}, year = {2020}, bdsk-url-1 = {https://doi.org/10.1007/s40722-020-00177-5} } - A Scoping Study to Determine the Location-Specific WEC Threshold Size for Wave-Powered AUV RechargingBlake P. Driscol, L. Andrew Gish, and Ryan G. CoeIEEE Journal of Oceanic Engineering, Nov 2020
The aim of this study is to determine the threshold wave energy converter (WEC) type and size to charge a fleet of U.S. Navy autonomous underwater vehicles (AUVs) in various geographic locations of interest. The U.S. Navy deploys AUVs in locations around the world that must be charged manually, decreasing their operational endurance and creating operational limitations. Ocean waves are a potential power source that can be converted into electricity using a WEC and stored using a battery. It would be beneficial to develop a WEC that could autonomously charge AUVs offshore. Numerous locations were analyzed to determine the minimum size of a WEC capable of providing sufficient charging power and offering a strategic advantage. By predicting the WEC efficiency (based on empirical equations) and wave resource (based on available data), electrical power generation across numerous WEC types and locations was compared in MATLAB. The generalized process developed here could be used to determine the required size and type of WECs to charge a fleet of AUVs in different locations around the world.
@article{Driscol:2020aa, author = {Driscol, Blake P. and Gish, L. Andrew and Coe, Ryan G.}, bibtex_show = true, date-added = {2020-10-07 14:02:25 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1109/JOE.2020.2973032}, issn = {1558-1691}, journal = {IEEE Journal of Oceanic Engineering}, keywords = {Batteries;Power generation;Computer interfaces;Sea surface;Generators;Surface waves;Hydrodynamics;Autonomous underwater vehicle (AUV);recharging;wave energy converter (WEC)}, pages = {1-10}, title = {A Scoping Study to Determine the Location-Specific {WEC} Threshold Size for Wave-Powered {AUV} Recharging}, url = {https://ieeexplore.ieee.org/document/9044418}, year = {2020}, bdsk-url-1 = {https://doi.org/10.1109/JOE.2020.2973032}, bdsk-url-2 = {https://ieeexplore.ieee.org/document/9044418} } - Extending Complex Conjugate Control to Nonlinear Wave Energy ConvertersDavid G. Wilson, Rush D. Robinett, Giorgio Bacelli, Ossama Abdelkhalik, and Ryan G. CoeJournal of Marine Science and Engineering, Jan 2020
This paper extends the concept of Complex Conjugate Control (CCC) of linear wave energy converters (WECs) to nonlinear WECs by designing optimal limit cycles with Hamiltonian Surface Shaping and Power Flow Control (HSSPFC). It will be shown that CCC for a regular wave is equivalent to a power factor of one in electrical power networks, equivalent to mechanical resonance in a mass-spring-damper (MSD) system, and equivalent to a linear limit cycle constrained to a Hamiltonian surface defined in HSSPFC. Specifically, the optimal linear limit cycle is defined as a second-order center in the phase plane projection of the constant energy orbit across the Hamiltonian surface. This concept of CCC described by a linear limit cycle constrained to a Hamiltonian surface will be extended to nonlinear limit cycles constrained to a Hamiltonian surface for maximum energy harvesting by the nonlinear WEC. The case studies presented confirm increased energy harvesting which utilizes nonlinear geometry realization for reactive power generation.
@article{Wilson:2020aa, author = {Wilson, David G. and Robinett, Rush D. and Bacelli, Giorgio and Abdelkhalik, Ossama and Coe, Ryan G.}, bibtex_show = true, date-added = {2020-10-07 14:01:13 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.3390/jmse8020084}, issn = {2077-1312}, journal = {Journal of Marine Science and Engineering}, month = jan, number = {2}, pages = {84}, publisher = {MDPI AG}, title = {Extending Complex Conjugate Control to Nonlinear Wave Energy Converters}, url = {http://dx.doi.org/10.3390/jmse8020084}, volume = {8}, year = {2020}, bdsk-url-1 = {http://dx.doi.org/10.3390/jmse8020084} } - Feedback Resonating Control for a Wave Energy ConverterGiorgio Bacelli, Victor Nevarez, Ryan G. Coe, and David G. WilsonIEEE Transactions on Industry Applications, Mar 2020
Through the use of advanced control techniques, wave energy converters (WECs) can achieve substantial increases in energy absorption. The motion of the WEC device is a significant contribution to the energy absorbed by the device. Reactive (complex conjugate) control maximizes the energy absorption due to the impedance matching. The issue with complex conjugate control is that, in general, the controller is noncausal, which requires prediction of the incoming waves. This article explores the potential of employing system identification techniques to build a causal transfer function that approximates the complex conjugate controller over a finite frequency band of interest. This approach is quite viable given the band-limited nature of ocean waves. The resulting controller is stable, and the average efficiency of the power captured by the causal controller in realistic ocean waves is 99%, when compared to the noncausal complex conjugate.
@article{Bacelli:2020aa, author = {Bacelli, Giorgio and Nevarez, Victor and G. Coe, Ryan and G. Wilson, David}, bibtex_show = true, date-added = {2020-10-07 12:37:21 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1109/TIA.2019.2958018}, groups = {AdvWecCntrls Pubs}, issn = {1939-9367}, journal = {IEEE Transactions on Industry Applications}, keywords = {Mathematical model;Impedance;Force;Impedance matching;Iron;Absorption;Transfer functions;Control systems;energy conversion;identifi-cation;impedance matching;resonance}, month = mar, number = {2}, pages = {{1862-1868}}, title = {Feedback Resonating Control for a Wave Energy Converter}, url = {https://ieeexplore.ieee.org/document/8926523}, volume = {56}, year = {2020}, bdsk-url-1 = {https://ieeexplore.ieee.org/document/8926523}, bdsk-url-2 = {https://doi.org/10.1109/TIA.2019.2958018} } - A Self-Tuning WEC Controller For Changing Sea StatesDominic D. Forbush, Giorgio Bacelli, Steven J. Spencer, and Ryan G. CoeIFAC-PapersOnLine, Berlin, Germany, Mar 202021th IFAC World Congress
A self-tuning proportional-integral control law prescribing motor torques was tested in experiment on a three degree-of-freedom wave energy converter. The control objective was to maximize electrical power. The control law relied upon an identified model of device intrinsic impedance to generate a frequency-domain estimate of the wave-induced excitation force and measurements of device velocities. The control law was tested in irregular sea-states that evolved over hours (a rapid, but realistic time-scale) and that changed instantly (an unrealistic scenario to evaluate controller response). For both cases, the controller converges to gains that closely approximate the post-calculated optimal gains for all degrees of freedom. Convergence to near-optimal gains occurred reliably over a sufficiently short time for realistic sea states. In addition, electrical power was found to be relatively insensitive to gain tuning over a broad range of gains, implying that an imperfectly tuned controller does not result in a large penalty to electrical power capture. An extension of this control law that allows for adaptation to a changing device impedance model over time is proposed for long-term deployments, as well as an approach to explicitly handle constraints within this architecture.
@article{Forbush:2020aa, address = {Berlin, Germany}, author = {Forbush, Dominic D. and Bacelli, Giorgio and Spencer, Steven J. and Coe, Ryan G.}, bibtex_show = true, booktitle = {Proceedings of the 21st IFAC World Congress}, date-added = {2020-10-07 12:35:17 -0600}, date-modified = {2025-10-02 07:51:20 -0600}, doi = {10.1016/j.ifacol.2020.12.1185}, groups = {AdvWecCntrls Pubs}, issn = {2405-8963}, journal = {IFAC-PapersOnLine}, keywords = {Wave energy, linear control, self-tuning control, spectral analysis, feedback control}, location = {Berlin, Germany}, note = {21th IFAC World Congress}, number = {2}, organization = {International Federation of Automatic Control}, pages = {12307-12312}, title = {A Self-Tuning {WEC} Controller For Changing Sea States}, url = {https://www.sciencedirect.com/science/article/pii/S2405896320315780}, volume = {53}, year = {2020}, bdsk-url-1 = {https://www.sciencedirect.com/science/article/pii/S2405896320315780}, bdsk-url-2 = {https://doi.org/10.1016/j.ifacol.2020.12.1185} } - FOSWEC dynamics and controls test reportRyan G. Coe, Giorgio Bacelli, Dominic Forbush, Steven J. Spencer, Kevin Dullea, Bret Bosma, and Pedro Lomonaco, Albuquerque, NM, Oct 2020
This report describes the testing of a model scale wave energy converter. This device, which uses two aps that pivot about a central platform when excited by waves, has a natural frequency within the range of the waves by which it is excited. The primary goal of this test was to assess the degree to which previously developed modeling, experimentation, and control design methods could be applied to a broad range of wave energy converter designs. Testing was conducted to identify a dynamic model for the impedance and excitation behavior of the device. Using these models, a series of closed loop tests were conducted using a causal impedance matching controller. This report provides a brief description of the results, as well as a summary of the device and ex- perimental design. The results show that the methods applied to this experimental device perform well and should be broadly applicable.
@techreport{Coe:2020ab, address = {Albuquerque, NM}, author = {Coe, Ryan G. and Bacelli, Giorgio and Forbush, Dominic and Spencer, Steven J. and Dullea, Kevin and Bosma, Bret and Lomonaco, Pedro}, bibtex_show = true, date-added = {2020-10-07 12:35:05 -0600}, date-modified = {2025-10-02 07:52:30 -0600}, doi = {10.2172/1717884}, groups = {AdvWecCntrls Pubs}, institution = {Sandia National Laboratories}, location = {Albuquerque, NM}, month = oct, number = {SAND2020-11695}, title = {{FOSWEC} dynamics and controls test report}, url = {https://www.osti.gov/servlets/purl/1717884/}, year = {2020}, bdsk-url-1 = {https://doi.org/10.2172/1717884} } - Initial conceptual demonstration of control co-design for WEC optimizationRyan G. Coe, Giorgio Bacelli, Sterling Olson, Vincent S. Neary, and Matthew B. R. TopperJournal of Ocean Engineering and Marine Energy, Oct 2020
While some engineering fields have benefited from systematic design optimization studies, wave energy converters have yet to successfully incorporate such analyses into practical engineering workflows. The current iterative approach to wave energy converter design leads to sub-optimal solutions. This short paper presents an open-source MATLAB toolbox for performing design optimization studies on wave energy converters where power take-off behavior and realistic constraints can be easily included. This tool incorporates an adaptable control co-design approach, in that a constrained optimal controller is used to simulate device dynamics and populate an arbitrary objective function of the user’s choosing. A brief explanation of the tool’s structure and underlying theory is presented. To demonstrate the capabilities of the tool, verify its functionality, and begin to explore some basic wave energy converter design relationships, three conceptual case studies are presented. In particular, the importance of considering (and constraining) the magnitudes of device motion and forces in design optimization is shown.
@article{Coe:2020aa, author = {Coe, Ryan G. and Bacelli, Giorgio and Olson, Sterling and Neary, Vincent S. and Topper, Matthew B. R.}, bibtex_show = true, da = {2020/11/07}, date = {2020-07-07}, date-added = {2020-10-07 12:35:05 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1007/s40722-020-00181-9}, id = {Coe2020}, isbn = {2198-6452}, journal = {Journal of Ocean Engineering and Marine Energy}, number = {4}, pages = {441--449}, title = {Initial conceptual demonstration of control co-design for {WEC} optimization}, ty = {JOUR}, url = {https://doi.org/10.1007/s40722-020-00181-9}, volume = {6}, year = {2020}, bdsk-url-1 = {https://www.techrxiv.org/articles/preprint/Initial_conceptual_demonstration_of_control_co-design_for_WEC_optimization/12928898}, bdsk-url-2 = {https://doi.org/10.36227/techrxiv.12928898.v1}, bdsk-url-3 = {https://doi.org/10.1007/s40722-020-00181-9} }
2019
- An approach for shear-stress based scour predictionRyan Geoffrey Coe, Alice Gillespie, Chris Clayton Chartrand, Mike Morrow, Mike Delos-Reyes, Fabian Wendt, Yi-Hsiang Yu, Tuba Oskan-Haller, Pedro Lomonaco, Jesse D. Roberts, Sterling Olson, and Craig JonesJan 2019
Scour beneath seafloor pipelines, cables, and other offshore infrastructure is a well-known problem. Recent interest in seafloor mounted wave energy converters brings another dynamic element into the traditional seafloor scour problem. In this paper, we consider the M3 Wave APEX device, which utilizes airflow between two flexible chambers to generate electricity from waves. In an initial at-sea deployment of a demonstration/experimental APEX in September 2014 off the coast of Oregon, scour beneath the device was observed. As sediment from the beneath the device was removed by scour, the device’s pitch orientation was shifted. This change in pitch orientation caused a degradation in power performance. Characterizing the scour associated with seafloor mounted wave energy conversion devices such as the M3 device is the objective of the present work.
@techreport{Coe:2019ab, address = {Albuquerque, NM}, author = {Coe, Ryan Geoffrey and Gillespie, Alice and Chartrand, Chris Clayton and Morrow, Mike and Delos-Reyes, Mike and Wendt, Fabian and Yu, Yi-Hsiang and Oskan-Haller, Tuba and Lomonaco, Pedro and Roberts, Jesse D. and Olson, Sterling and Jones, Craig}, bibtex_show = true, date-added = {2021-02-13 16:37:06 -0700}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.2172/1493823}, institution = {Sandia National Laboratories}, month = jan, number = {SAND2019-0865}, place = {United States}, title = {An approach for shear-stress based scour prediction}, url = {https://www.osti.gov/biblio/1493823}, year = {2019}, bdsk-url-1 = {https://www.osti.gov/biblio/1493823}, bdsk-url-2 = {https://doi.org/10.2172/1493823} } - The Wave Energy Converter Control Competition: OverviewJohn Ringwood, Francesco Ferri, Nathan Tom, Kelley Ruehl, Nicols Faedo, Giorgio Bacelli, Yi-Hsiang Yu, and Ryan G. CoeIn Proceedings of the ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering, Jun 2019V010T09A035
Over the past two years, a wave energy converter control systems competition (WECCCOMP) has been in progress, with the objective of comparing different wave energy converter (WEC) control paradigms on a standard benchmark problem. The target system is a point absorber, corresponding to a single float with an absolute reference, of the WaveStar WEC prototype. The system was modelled in WEC-Sim, with the hydrodynamic parameters validated against tank test data. Competitors were asked to design and implement a WEC control system for this model, with performance evaluated across six sea states. The evaluation criteria included a weighted combination of average converted power, peak/average power, and the degree to which the system physical constraints were exploited or temporarily exceeded.This paper provides an overview of the competition, which includes a comparative evaluation of the entries and their performance on the simulation model. It is intended that this paper will act as an anchor presentation in a special session on WECCCOMP at OMAE 2019, with other papers in the special session contributed by the competitors, describing in detail the control algorithms and the results achieved over the various sea states.
@inproceedings{Ringwood:2019aa, address = {Glasgow, Scotland, UK}, author = {Ringwood, John and Ferri, Francesco and Tom, Nathan and Ruehl, Kelley and Faedo, Nicols and Bacelli, Giorgio and Yu, Yi-Hsiang and Coe, Ryan G.}, bibtex_show = true, booktitle = {Proceedings of the ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering}, date-added = {2020-10-07 15:20:01 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1115/OMAE2019-95216}, eprint = {https://asmedigitalcollection.asme.org/OMAE/proceedings-pdf/OMAE2019/58899/V010T09A035/6444644/v010t09a035-omae2019-95216.pdf}, month = jun, note = {V010T09A035}, series = {International Conference on Offshore Mechanics and Arctic Engineering}, title = {{The Wave Energy Converter Control Competition: Overview}}, url = {https://doi.org/10.1115/OMAE2019-95216}, volume = {10: Ocean Renewable Energy}, year = {2019}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2019-95216} } - WEC Optimization Tool Scoping ReportRyan G. Coe, Zachary Morrell, Giorgio Bacelli, Dominic Forbush, Hannah Mankle, Bryony DuPont, and Vincent S. NearyJun 2019
@techreport{Coe:2019ac, address = {Albuquerque, NM}, author = {Coe, Ryan G. and Morrell, Zachary and Bacelli, Giorgio and Forbush, Dominic and Mankle, Hannah and DuPont, Bryony and Neary, Vincent S.}, bibtex_show = true, date-added = {2020-10-07 14:09:54 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.2172/1762915}, institution = {Sandia National Laboratories}, month = jun, number = {SAND2019-7580}, title = {{WEC} Optimization Tool Scoping Report}, url = {https://www.osti.gov/biblio/1762915}, year = {2019}, bdsk-url-1 = {https://www.osti.gov/biblio/1762915}, bdsk-url-2 = {https://doi.org/10.2172/1762915} } - Development of WEC Design Loads: A Comparison of Numerical and Experimental ApproachesBrian J. Rosenberg, Tim R. Mundon, Ryan G. Coe, Eliot W. Quon, Chris C. Chartrand, Yi-Hsiang Yu, and Jennifer A. Van RijIn Proceedings of the 13th European Wave and Tidal Energy Conference (EWTEC2019), Jun 2019
The development of accurate design loads is a critical part of the design of a wave energy converter (WEC). In this paper, we evaluate the impact of different approaches to determining extreme wave loading on the Triton WEC using a combination of mid-fidelity and high-fidelity numerical modeling tools, complemented by scaled physical model tests. The mid-fidelity approach used is a time-domain model based on linearized potential flow hydrodynamics while the high-fidelity modeling tool is an unsteady RANS CFD model. A 1:30 scale physical model of the Triton WEC was tested at the Oregon State University Large Wave Flume. A comparison will be presented between the design loads predicted by the mid-fidelity model, the CFD model, and the physical model tests, and suggestions for best practices will be offered.
@inproceedings{Rosenberg:2019aa, address = {Naples, Italy}, author = {Rosenberg, Brian J. and Mundon, Tim R. and Coe, Ryan G. and Quon, Eliot W. and Chartrand, Chris C. and Yu, Yi-Hsiang and Van Rij, Jennifer A.}, bibtex_show = true, booktitle = {Proceedings of the 13th European Wave and Tidal Energy Conference (EWTEC2019)}, date-added = {2020-10-07 14:07:50 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, title = {Development of {WEC} Design Loads: A Comparison of Numerical and Experimental Approaches}, url = {https://www.osti.gov/servlets/purl/1572263}, year = {2019}, bdsk-url-1 = {https://www.osti.gov/servlets/purl/1572263} } - Numerical modelling of a point-absorbing WEC model using DualSPHysics coupled with a multiphysics libraryBonaventura Tagliafierro, Alejandro JC Crespo, José M Domı́nguez, Orlando Garcı́a-Feal, Moncho Gómez-Gesteira, Ricardo B Canelas, Ryan G. Coe, Giorgio Bacelli, Hancheol Cho, Steve J Spencer, and Giacomo ViccioneIn Proceedings of the 13th European Wave and Tidal Energy Conference (EWTEC), Jun 2019
The aim of this work is to present the capabilities of the meshless numerical model named DualSPHysics, which coupled with a multiphysics library, is able to reproduce the interaction between waves and a floating wave energy converter(WEC).This is a challenging problem to be simulated with a numerical model since it includes not only the non-linear wave-structure interaction, but also the mechanical constraints of the floating WEC. DualSPHysics, which is a SPH-based code, is herein coupled with the Chrono library. This library is developed as a general-purpose simulation package for multi-body problems. The library is implemented under the DualSPHysics code, providing an integrated interface to define and run arbitrarily defined fluid-structure-structure coupled systems under the same framework. The DualSPHysics-Chrono coupled model was already validated for fluid-structure-structure interaction cases and it is here applied to simulate a floating point absorber. The model-scale WEC was designed and tested in MASK basin. The WEC is independently actuated in heave, surge, and pitch (all the degrees of freedom in a single plane). Tests have been conducted for the investigation of control to improve power generation and load reduction and to study system identification (SID) and model validation. Some of those tests are here reproduced with the proposed numerical tool. Numerical forces exerted by monochromatic waves onto the floating point absorber are compared with the experimental data and good agreement is observed. Therefore, DualSPHysics-Chrono is proposed as a design tool to improve the efficiency and survivability of this floating WEC, and could eventually be used to model the full PTO system,a challenging task for most CFD software.
@inproceedings{Tagliafierro:2019aa, address = {Naples, Italy}, author = {Tagliafierro, Bonaventura and Crespo, Alejandro JC and Dom{\'\i}nguez, Jos{\'e} M and Garc{\'\i}a-Feal, Orlando and G{\'o}mez-Gesteira, Moncho and Canelas, Ricardo B and Coe, Ryan G. and Bacelli, Giorgio and Cho, Hancheol and Spencer, Steve J and Viccione, Giacomo}, bibtex_show = true, booktitle = {Proceedings of the 13th European Wave and Tidal Energy Conference (EWTEC)}, date-added = {2020-10-07 14:05:57 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, keywords = {CFD, Chrono, Multiphysics, Numerical modelling, Point absorber, DualSPHysics}, title = {Numerical modelling of a point-absorbing {WEC} model using {DualSPHysics} coupled with a multiphysics library}, url = {https://www.researchgate.net/publication/338375216_Numerical_modelling_of_a_point-absorbing_WEC_model_using_DualSPHysics_coupled_with_a_multiphysics_library}, year = {2019}, bdsk-url-1 = {https://www.researchgate.net/profile/Ryan_Coe/publication/338375216_Numerical_modelling_of_a_point-absorbing_WEC_model_using_DualSPHysics_coupled_with_a_multiphysics_library/links/5e0f91a04585159aa4b10cf2/Numerical-modelling-of-a-point-absorbing-WEC-model-using-DualSPHysics-coupled-with-a-multiphysics-library.pdf}, bdsk-url-2 = {https://www.researchgate.net/publication/338375216_Numerical_modelling_of_a_point-absorbing_WEC_model_using_DualSPHysics_coupled_with_a_multiphysics_library} } - Wave-Powered AUV Recharging: A Feasibility StudyBlake P. Driscol, Andrew Gish, and Ryan G. CoeIn Proceedings of the ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering, Jun 2019V010T09A023
The aim of this study is to determine whether multiple U.S. Navy autonomous underwater vehicles (AUVs) could be supported using a small, heaving wave energy converter (WEC). The U.S. Navy operates numerous AUVs that need to be charged periodically onshore or onboard a support ship. Ocean waves provide a vast source of energy that can be converted into electricity using a wave energy converter and stored using a conventional battery. The Navy would benefit from the development of a wave energy converter that could store electrical power and autonomously charge its AUVs offshore. A feasibility analysis is required to ensure that the WEC could support the energy needs of multiple AUVs, remain covert, and offer a strategic military advantage. This paper investigates the Navy’s power demands for AUVs and decides whether or not these demands could be met utilizing various measures of WEC efficiency. Wave data from a potential geographic region is analyzed to determine optimal locations for the converter in order to meet the Navy’s power demands and mission set.
@inproceedings{Driscol:2019aa, address = {Glasgow, Scotland, UK}, author = {Driscol, Blake P. and Gish, Andrew and Coe, Ryan G.}, bibtex_show = true, booktitle = {Proceedings of the ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering}, date-added = {2020-10-07 13:01:58 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1115/OMAE2019-95383}, eprint = {https://asmedigitalcollection.asme.org/OMAE/proceedings-pdf/OMAE2019/58899/V010T09A023/6444786/v010t09a023-omae2019-95383.pdf}, month = jun, note = {V010T09A023}, series = {International Conference on Offshore Mechanics and Arctic Engineering}, title = {{Wave-Powered AUV Recharging: A Feasibility Study}}, url = {https://doi.org/10.1115/OMAE2019-95383}, volume = {10: Ocean Renewable Energy}, year = {2019}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2019-95383} } - Nonlinear WEC Optimized Geometric Buoy Design for Efficient Reactive Power RequirementsDavid G. Wilson, Rush D. Robinett, Giorgio Bacelli, Ossama Abdelkhalik, Wayne W. Weaver, and Ryan CoeIn OCEANS 2019 MTS/IEEE SEATTLE, Oct 2019
This paper presents a nonlinear geometric buoy design for Wave Energy Converters (WECs). A nonlinear dynamic model is presented for an hour glass (HG) configured WEC. The HG buoy operates in heave motion or as a single Degree-of-Freedom (DOF). The unique formulation of the interaction between the buoy and the waves produces a nonlinear stiffening effect that provides the actual energy storage or reactive power during operation. A Complex Conjugate Control (C3) with a practical Proportional-Derivative (PD) controller is employed to optimize power absorption for off-resonance conditions and applied to a linear right circular cylinder (RCC) WEC. For a single frequency the PDC3 RCC buoy is compared with the HG buoy design. A Bretschneider spectrum of wave excitation input conditions are reviewed and evaluated for the HG buoy. Numerical simulations demonstrate power and energy capture for the HG geometric buoy design which incorporates and capitalizes on the nonlinear geometry to provide reactive power for the single DOF WEC. By exploiting the nonlinear physics in the HG design simplified operational performance is observed when compared to an optimized linear cylindrical WEC. The HG steepness angle α with respect to the wave is varied and initially optimized for improved energy capture.
@inproceedings{Wilson:2019aa, address = {Seattle, WA}, author = {Wilson, David G. and Robinett, Rush D. and Bacelli, Giorgio and Abdelkhalik, Ossama and Weaver, Wayne W. and Coe, Ryan}, bibtex_show = true, booktitle = {OCEANS 2019 MTS/IEEE SEATTLE}, date-added = {2020-10-07 13:00:57 -0600}, date-modified = {2025-10-02 07:56:09 -0600}, doi = {10.23919/OCEANS40490.2019.8962670}, issn = {0197-7385}, keywords = {design engineering;nonlinear programming;offshore installations;PD control;power generation control;reactive power control;wave power generation;linear right circular cylinder WEC;single frequency;PDC3 RCC buoy;HG buoy design;wave excitation input conditions;HG geometric buoy design;nonlinear geometry;single DOF WEC;nonlinear physics;HG design;optimized linear cylindrical WEC;HG steepness angle α;improved energy capture;nonlinear WEC optimized geometric buoy design;efficient reactive power requirements;nonlinear geometric buoy design;wave energy converters;nonlinear dynamic model;nonlinear stiffening effect;actual energy storage;complex conjugate control;power absorption;reactive power;feedback control;wave energy converter}, month = oct, pages = {1-6}, title = {Nonlinear {WEC} Optimized Geometric Buoy Design for Efficient Reactive Power Requirements}, url = {https://ieeexplore.ieee.org/document/8962670}, year = {2019}, bdsk-url-1 = {https://doi.org/10.23919/OCEANS40490.2019.8962670} } - WEC Array Networked Microgrid Control Design and Energy Storage System RequirementsWayne W. Weaver, Alex Hagmuller, Max Ginsburg, David G. Wilson, Giorgio Bacelli, Rush D. Robinett, Ryan Coe, and Budi GunawanIn OCEANS 2019 MTS/IEEE SEATTLE, Oct 2019
Wave Energy Converter (WEC) technologies transform power from the waves to the electrical grid. WEC system components are investigated that support the performance, stability, and efficiency as part of a WEC array. To this end, Aquaharmonics Inc took home the $1.5 million grand prize in the 2016 U.S. Department of Energy Wave Energy Prize, an 18-month design-build-test competition to increase the energy capture potential of wave energy devices. Aquaharmonics intends to develop, build, and perform open ocean testing on a 1: 7 scale device. Preliminary wave tank testing on the mechanical system of the 1: 20 scale device has yielded a data-set of operational conditions and performance. In this paper, the Hamiltonian surface shaping and power flow control (HSSPFC) method is used in conjunction with scaled wave tank test data to explore the design space for the electrical transmission of energy to the shore-side power grid. Of primary interest is the energy storage system (ESS) that will electrically link the WEC to the shore. Initial analysis results contained in this paper provide a trade-off in storage device performance and design selection.
@inproceedings{Weaver:2019aa, address = {Seattle, WA}, author = {Weaver, Wayne W. and Hagmuller, Alex and Ginsburg, Max and Wilson, David G. and Bacelli, Giorgio and Robinett, Rush D. and Coe, Ryan and Gunawan, Budi}, bibtex_show = true, booktitle = {OCEANS 2019 MTS/IEEE SEATTLE}, date-added = {2020-10-07 13:00:47 -0600}, date-modified = {2025-10-02 07:57:29 -0600}, doi = {10.23919/OCEANS40490.2019.8962576}, issn = {0197-7385}, keywords = {control system synthesis;distributed power generation;energy storage;load flow control;power generation control;power grids;power system stability;power transmission control;wave power generation;power flow control method;scaled wave tank test data;WEC array networked microgrid control design;energy storage system;wave energy converter technologies;electrical grid;open ocean testing;mechanical system;Hamiltonian surface shaping;electrical transmission;shore-side power grid;preliminary wave tank testing}, month = oct, pages = {1-6}, title = {{WEC} Array Networked Microgrid Control Design and Energy Storage System Requirements}, url = {https://ieeexplore.ieee.org/document/8962576}, year = {2019}, bdsk-url-1 = {https://doi.org/10.23919/OCEANS40490.2019.8962576} } - A Wave Energy Converter Design Load Case StudyJennifer Van Rij, Yi-Hsiang Yu, Yi Guo, and Ryan G. CoeJournal of Marine Science and Engineering, Jul 2019
This article presents an example by which design loads for a wave energy converter (WEC) might be estimated through the various stages of the WEC design process. Unlike previous studies, this study considers structural loads, for which, an accurate assessment is crucial to the optimization and survival of a WEC. Three levels of computational fidelity are considered. The first set of design load approximations are made using a potential flow frequency-domain boundary-element method with generalized body modes. The second set of design load approximations are made using a modified version of the linear-based time-domain code WEC-Sim. The final set of design load simulations are realized using computational fluid dynamics coupled with finite element analysis to evaluate the WEC’s loads in response to both regular and focused waves. This study demonstrates an efficient framework for evaluating loads through each of the design stages. In comparison with experimental and high-fidelity simulation results, the linear-based methods can roughly approximate the design loads and the sea states at which they occur. The high-fidelity simulations for regular wave responses correspond well with experimental data and appear to provide reliable design load data. The high-fidelity simulations of focused waves, however, result in highly nonlinear interactions that are not predicted by the linear-based most-likely extreme response design load method.
@article{Rij:2019aa, author = {Rij, Jennifer Van and Yu, Yi-Hsiang and Guo, Yi and Coe, Ryan G.}, bibtex_show = true, date-added = {2020-10-07 12:58:13 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.3390/jmse7080250}, issn = {2077-1312}, journal = {Journal of Marine Science and Engineering}, month = jul, number = {8}, pages = {250}, publisher = {MDPI AG}, title = {A Wave Energy Converter Design Load Case Study}, url = {http://dx.doi.org/10.3390/jmse7080250}, volume = {7}, year = {2019}, bdsk-url-1 = {http://dx.doi.org/10.3390/jmse7080250} } - A Benchmarking Exercise on Estimating Extreme Environmental Conditions: Methodology and Baseline ResultsAndreas F. Haselsteiner, Ryan G. Coe, Lance Manuel, Phong T. T. Nguyen, Nevin Martin, and Aubrey Eckert-GallupIn Proceedings of the ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering, Jun 2019V003T02A049
A wide range of methods have been proposed for the derivation of environmental contours for marine structures that must meet reliability targets. An environmental contour is a set of joint extremes of environmental conditions associated with a target return period. In general, environmental contour methods help with the prediction of some future critical combinations of environmental conditions (e.g., wind, waves, current) at a location of interest based on a limited dataset, thus allowing designers to ensure a prescribed structural reliability. In fact, some of these contour methods are specifically recommended by technical specifications and standards as part of a design process. This paper outlines the rules and procedures for a collaborative benchmarking exercise — focused on open comparison — in which researchers are invited to develop and present their own contour derivation approaches based on common datasets that will be available to all. Hindcast and observational datasets are considered and two exercises are planned: One focuses on applying environmental contour methods to a wide range of datasets and the other focuses on uncertainty characterization. Besides describing the benchmark’s methodology, this paper presents baseline results of computed contours following current recommendations. The overall goals of this endeavor are: (i) to work towards the development of more robust statistical models and contour construction methods, (ii) to encourage increased discussion in the international research community and among practitioners, and (iii) to support ongoing efforts to improve technical specifications and standards.
@inproceedings{Haselsteiner:2019aa, address = {Glasgow, Scotland, UK}, author = {Haselsteiner, Andreas F. and Coe, Ryan G. and Manuel, Lance and Nguyen, Phong T. T. and Martin, Nevin and Eckert-Gallup, Aubrey}, bibtex_show = true, booktitle = {Proceedings of the ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering}, date-added = {2020-10-07 12:54:00 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1115/OMAE2019-96523}, month = jun, note = {V003T02A049}, series = {International Conference on Offshore Mechanics and Arctic Engineering}, title = {{A Benchmarking Exercise on Estimating Extreme Environmental Conditions: Methodology and Baseline Results}}, url = {https://doi.org/10.1115/OMAE2019-96523}, volume = {3: Structures, Safety, and Reliability}, year = {2019}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2019-96523} } - On the Development of an Efficient Surrogate Model for Predicting Long-Term Extreme Loads on a Wave Energy ConverterPhong T. T. Nguyen, Lance Manuel, and Ryan G. CoeJournal of Offshore Mechanics and Arctic Engineering, Mar 2019061103
Accurate prediction of long-term extreme loads is essential for the design of wave energy converters (WECs), but it is also computationally demanding due to the low probabilities associated with their occurrence. Although a full long-term probabilistic analysis using integration over all sea states or Monte Carlo simulation (MCS) may be used, these methods can be prohibitively expensive when individual response simulations are complex and time-consuming. The application of polynomial chaos expansion (PCE) schemes to allow the propagation of uncertainty from the environment through the stochastic sea surface elevation process and ultimately to WEC extreme load response prediction is the focus in this study. A novel approach that recognizes the role of long-term ocean climate uncertainty (in sea state variables such as significant wave height and spectral peak period) as well as short-term response uncertainty arising from the unique random phasing in irregular wave trains is presented and applied to a single-body point-absorber WEC device model. Stochastic simulation results in time series realizations of various response processes for the case-study WEC. We employ environmental data from a possible deployment site in Northern California (NDBC 46022) to assess long-term loads. MCS computations are also performed and represent the “truth” system against which the efficiency and accuracy of the PCE surrogate model are assessed. Results suggest that the PCE approach requires significantly less effort to obtain comparable estimates to MCS.
@article{Nguyen:2019aa, author = {Nguyen, Phong T. T. and Manuel, Lance and Coe, Ryan G.}, bibtex_show = true, date-added = {2020-10-07 12:53:41 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1115/1.4042944}, eprint = {https://asmedigitalcollection.asme.org/offshoremechanics/article-pdf/141/6/061103/6403607/omae\_141\_6\_061103.pdf}, issn = {0892-7219}, journal = {Journal of Offshore Mechanics and Arctic Engineering}, month = mar, note = {061103}, number = {6}, title = {{On the Development of an Efficient Surrogate Model for Predicting Long-Term Extreme Loads on a Wave Energy Converter}}, url = {https://doi.org/10.1115/1.4042944}, volume = {141}, year = {2019}, bdsk-url-1 = {https://doi.org/10.1115/1.4042944} } - CFD design-load analysis of a two-body wave energy converterRyan G. Coe, Brian J. Rosenberg, Eliot W. Quon, Chris C. Chartrand, Yi-Hsiang Yu, Jennifer Van Rij, and Tim R. MundonJournal of Ocean Engineering and Marine Energy, Mar 2019
Wave energy converters (WECs) must survive in a wide variety of conditions while minimizing structural costs, so as to deliver power at cost-competitive rates. Although engineering design and analysis tools used for other ocean systems, such as offshore structures and ships, can be applied, the unique nature and limited historical experience of WEC design necessitates assessment of the effectiveness of these methods for this specific application. This paper details a study to predict extreme loading in a two-body WEC using a combination of mid-fidelity and high-fidelity numerical modeling tools. Here, the mid-fidelity approach is a time-domain model based on linearized potential flow hydrodynamics and the high-fidelity modeling tool is an unsteady Reynolds-averaged Navier–Stokes model. In both models, the dynamics of the WEC power take-off and mooring system have been included. For the high-fidelity model, two design wave approaches (an equivalent regular wave and a focused wave) are used to estimate the worst case wave forcing within a realistic irregular sea state.These simplified design wave approaches aim to capture the extreme response of the WEC within a feasible amount of computational effort. When compared to the mid-fidelity model results in a long-duration irregular sea, the short-duration design waves simulated in CFD produce upper percentile load responses, hinting at the suitability of these two approaches.
@article{Coe:2019aa, author = {Coe, Ryan G. and Rosenberg, Brian J. and Quon, Eliot W. and Chartrand, Chris C. and Yu, Yi-Hsiang and Van Rij, Jennifer and Mundon, Tim R.}, bibtex_show = true, da = {2019/05/01}, date-added = {2020-10-07 12:52:26 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1007/s40722-019-00129-8}, id = {Coe2019}, isbn = {2198-6452}, journal = {Journal of Ocean Engineering and Marine Energy}, number = {2}, pages = {99--117}, title = {{CFD} design-load analysis of a two-body wave energy converter}, ty = {JOUR}, url = {https://doi.org/10.1007/s40722-019-00129-8}, volume = {5}, year = {2019}, bdsk-url-1 = {https://doi.org/10.1007/s40722-019-00129-8} } - Wave tank and bench-top control testing of a wave energy converterGiorgio Bacelli, Steven J. Spencer, David C. Patterson, and Ryan G. CoeApplied Ocean Research, Mar 2019
An increasing number of experiments are being conducted to study the design and performance of wave energy converters. Often in these tests, a real-time realization of prospective control algorithms is applied in order to assess and optimize energy absorption as well as other factors. This paper details the design and execution of an experiment for evaluating the capability of a model-scale WEC to execute basic control algorithms. Model-scale hardware, system, and experimental design are considered, with a focus on providing an experimental setup capable of meeting the dynamic requirements of a control system. To more efficiently execute such tests, a dry bench testing method is proposed and utilized to allow for controller tuning and to give an initial assessment of controller performance; this is followed by wave tank testing. The trends from the dry bench test and wave tank test results show good agreement with theory and confirm the ability of a relatively simple feedback controller to substantially improve energy absorption. Additionally, the dry bench testing approach is shown to be an effective and efficient means of designing and testing both controllers and actuator systems for wave energy converters.
@article{Bacelli:2019aa, author = {Bacelli, Giorgio and Spencer, Steven J. and Patterson, David C. and Coe, Ryan G.}, bibtex_show = true, date-added = {2020-10-07 12:37:21 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1016/j.apor.2018.09.009}, file = {:Bacelli2019.pdf:PDF}, groups = {AdvWecCntrls Pubs}, issn = {0141-1187}, journal = {Applied Ocean Research}, keywords = {Wave energy converter (WEC), Control, Wave tank, Model-scale testing}, owner = {rcoe}, pages = {351 - 366}, timestamp = {2018.12.16}, title = {Wave tank and bench-top control testing of a wave energy converter}, url = {http://www.sciencedirect.com/science/article/pii/S0141118717307484}, volume = {86}, year = {2019}, bdsk-url-1 = {http://www.sciencedirect.com/science/article/pii/S0141118717307484}, bdsk-url-2 = {https://doi.org/10.1016/j.apor.2018.09.009} } - Evaluation of predictionless control for wave energy convertersHancheol Cho, Giorgio Bacelli, Victor Nevarez, Felipe Wilches-Bernaland, and Ryan G. CoeIn Proceedings of the 13th European Wave and Tidal Energy Conference (EWTEC2019), Sep 2019
In this paper, a feedback control strategy for a wave energy converter (WEC) with no prediction is proposed that provides performance rivaling a prediction-based controller, even when assuming perfect prediction. This innovative control scheme is derived first by abstracting the WEC in the same structure as an electrical circuit and by applying the Jacobi’s maximum power transfer law to optimize WEC power absorption. By considering the implementation of complex conjugate control problem over a finite bandwidth, a causal controller can be realized. This causal controller can be defined such that its frequency response follows that of the complex conjugate controller as closely as possible using fitting techniques such as system identification. This suboptimal controller requires no prediction and only the device velocity needs to be measured to calculate control signals. Additionally, a model predictive controller (MPC) is designed to handle constraints with minimal (1-step) prediction. In implementing this MPC, prediction of wave elevation is not required either and the standard MPC block available in the MathWorks MPC toolbox can be employed, which is of great importance for practical applications. The MPC behaves as a predesigned causal controller and also acts as a supervisory controller to prevent the device from hitting end-stops. The performance of the proposed causal controllers and the MPC is compared with the complex conjugate controller in terms of the mean power absorption and it is shown that more than 90% of the theoretical maximum can be achieved.
@inproceedings{Cho:2019aa, address = {Napoli, Italy}, author = {Cho, Hancheol and Bacelli, Giorgio and Nevarez, Victor and Wilches-Bernaland, Felipe and Coe, Ryan G.}, bibtex_show = true, booktitle = {Proceedings of the 13th European Wave and Tidal Energy Conference (EWTEC2019)}, date-added = {2020-10-07 12:35:46 -0600}, date-modified = {2025-10-02 07:59:02 -0600}, groups = {AdvWecCntrls Pubs}, month = sep, title = {Evaluation of predictionless control for wave energy converters}, url = {https://www.osti.gov/biblio/1641422}, year = {2019}, bdsk-url-1 = {https://www.researchgate.net/publication/338374910_Evaluation_of_predictionless_control_for_wave_energy_converters} } - Model Predictive Control Tuning by Inverse Matching for a Wave Energy ConverterHancheol Cho, Giorgio Bacelli, and Ryan G. CoeEnergies, Oct 2019
This paper investigates the application of a method to find the cost function or the weight matrices to be used in model predictive control (MPC) such that the MPC has the same performance as a predesigned linear controller in state-feedback form when constraints are not active. This is potentially useful when a successful linear controller already exists and it is necessary to incorporate the constraint-handling capabilities of MPC. This is the case for a wave energy converter (WEC), where the maximum power transfer law is well-understood. In addition to solutions based on numerical optimization, a simple analytical solution is also derived for cases with a short prediction horizon. These methods are applied for the control of an empirically-based WEC model. The results show that the MPC can be successfully tuned to follow an existing linear control law and to comply with both input and state constraints, such as actuator force and actuator stroke.
@article{Cho:2019ab, author = {Cho, Hancheol and Bacelli, Giorgio and Coe, Ryan G.}, bibtex_show = true, date-added = {2020-10-07 12:35:46 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.3390/en12214158}, groups = {AdvWecCntrls Pubs}, issn = {1996-1073}, journal = {Energies}, month = oct, number = {21}, pages = {4158}, publisher = {MDPI AG}, title = {Model Predictive Control Tuning by Inverse Matching for a Wave Energy Converter}, url = {http://dx.doi.org/10.3390/en12214158}, volume = {12}, year = {2019}, bdsk-url-1 = {http://dx.doi.org/10.3390/en12214158} } - Advanced WEC Dynamics and Controls MASK3 TestRyan G. Coe, Giorgio Bacelli, Steven J. Spencer, Dominic Forbush, and Kevin DulleaDec 2019
@techreport{Coe:2019ae, address = {Albuquerque, NM}, author = {Coe, Ryan G. and Bacelli, Giorgio and Spencer, Steven J. and Forbush, Dominic and Dullea, Kevin}, bibtex_show = true, date-added = {2020-10-07 12:35:05 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.2172/1592850}, groups = {AdvWecCntrls Pubs}, institution = {Sandia National Laboratories}, month = dec, number = {SAND2019-15428}, title = {Advanced {WEC} Dynamics and Controls {MASK3} Test}, url = {https://www.osti.gov/biblio/1592850-advanced-wec-dynamics-controls-mask3-test}, year = {2019}, bdsk-url-1 = {https://www.osti.gov/biblio/1592850-advanced-wec-dynamics-controls-mask3-test}, bdsk-url-2 = {https://doi.org/10.2172/1592850} } - A summary of the Advanced WEC Dynamics and Control projectRyan G. Coe, and Giorgio BacelliNov 2019
This report serves as a comprehensive summary of the work completed by the "Advanced WEC Dynamics and Controls project" during the period of 2013-2019. This project was first envisioned to simply consider the question of designing a controller for wave energy converters (WECs), without a complete recognition of the broader considerations that such a task must necessarily examine. This document describes both the evolution of the project scope and the key findings produced. The basic goal of the project has been to deliver tractable methodologies and work flows that WEC designers can use to improve the performance of their machines. Engineering solutions, which may offer 80% of the impact, but require 20% of the effort compared to a perfect result (which may be many years of development down the road) were preferred. With this doctrine, the work of the project often involved translating existing methods that have been successfully developed and applied for other fields, into the application area of wave energy.
@techreport{Coe:2019ad, address = {Albuquerque, NM}, author = {Coe, Ryan G. and Bacelli, Giorgio}, bibtex_show = true, date-added = {2020-10-07 12:35:05 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.2172/1592944}, groups = {AdvWecCntrls Pubs}, institution = {Sandia National Laboratories}, month = nov, number = {SAND2019-14355}, place = {United States}, title = {A summary of the {Advanced WEC Dynamics and Control} project}, url = {https://www.osti.gov/biblio/1592944}, year = {2019}, bdsk-url-1 = {https://doi.org/10.2172/1592944}, bdsk-url-2 = {https://www.osti.gov/biblio/1592944-summary-advanced-wec-dynamics-control-project} }
2018
- Feedback resonating controller for a heaving point absorber WECGiorgio Bacelli, Victor Nevarez, Ryan G. Coe, and David WilsonIn Proceedings of the 6th Marine Energy Technology Symposium (METS), Nov 2018
@inproceedings{Bacelli:2018aa, address = {Washington, D.C.}, author = {Bacelli, Giorgio and Nevarez, Victor and Coe, Ryan G. and Wilson, David}, bibtex_show = true, booktitle = {Proceedings of the 6th Marine Energy Technology Symposium (METS)}, date-added = {2020-10-07 14:24:19 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, title = {Feedback resonating controller for a heaving point absorber {WEC}}, url = {https://energy.sandia.gov/download/43544/}, year = {2018}, bdsk-url-1 = {https://energy.sandia.gov/download/43544/} } - Hydraulic PTO model emulator for WEC tank testsSimone Giorgi, Ronan Costello, Giorgio Bacelli, and Ryan G. CoeIn 2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM), Jun 2018
In order to accelerate the overall power take off (PTO) design effort and to cheaply evaluate alternative designs, the construction of the real hydraulic PTO can be replaced with the design of a hydraulic PTO model emulator. This has the added advantage that it can be applied at model testing scales, where real hydraulic hardware would not give performance, representative of the full scale PTO (most likely, the scale PTO hardware and the full PTO hardware would be completely different but, even if similar, the operating points and performance would be very dissimilar). Finally, and most importantly for this work, the emulated PTO presents realistic interface to the controller while the emulated force signals are actuated by an electric motor. This paper reports the main results from a collaborative project between Wave Venture Ltd. and SANDIA National Laboratories, focused on the development of a hydraulic PTO model emulator, in order to carry out wave tank tests with the new SANDIA wave energy converter (WEC).
@inproceedings{Giorgi:2018aa, address = {Amalfi, Italy}, author = {Giorgi, Simone and Costello, Ronan and Bacelli, Giorgio and Coe, Ryan G.}, bibtex_show = true, booktitle = {2018 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM)}, date-added = {2020-10-07 14:23:34 -0600}, date-modified = {2025-10-02 08:00:44 -0600}, doi = {10.1109/SPEEDAM.2018.8445383}, keywords = {design engineering;hydraulic systems;tanks (containers);hydraulic PTO model emulator;hydraulic hardware;WEC tank tests;overall power take off design;SANDIA wave energy converter;Hydraulic systems;Force;Pumps;Pistons;Hardware;Laboratories;Control systems;Hydraulic PTO;wave energy;wave tank experiments;PTO emulator;electro-hydraulic control;variable pressure system}, month = jun, pages = {1257-1262}, title = {Hydraulic {PTO} model emulator for {WEC} tank tests}, url = {https://ieeexplore.ieee.org/document/8445383}, year = {2018}, bdsk-url-1 = {https://doi.org/10.1109/SPEEDAM.2018.8445383}, bdsk-url-2 = {https://ieeexplore.ieee.org/document/8445383} } - On the Development of an Efficient Surrogate Model for Predicting Long-Term Extreme Loads on a Wave Energy ConverterPhong T. T. Nguyen, Lance Manuel, and Ryan G. CoeIn Proceedings of the ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering, Jun 2018V010T09A035
Accurate prediction of long-term extreme loads is essential for the design of wave energy converters (WECs), but it is also computationally demanding due to the low probabilities associated with their occurrence. While a full long-term probabilistic analysis using integration over all sea states or Monte Carlo Simulation (MCS) may be used, these methods can be prohibitively expensive when individual response simulations are complex and time-consuming. The application of polynomial chaos expansion (PCE) schemes to allow the propagation of uncertainty from the environment through the stochastic sea surface elevation process and ultimately to WEC extreme load response prediction is the focus in this study. A novel approach that recognizes the role of long-term ocean climate uncertainty (in sea state variables like significant wave height and spectral peak period) as well as short-term response uncertainty arising from irregular wave trains is presented and applied to a single-body point-absorber WEC device model. Stochastic simulation results in time series realizations of various response processes for the case-study WEC. We employ environmental data from a possible deployment site in Northern California (NDBC 46022) to assess long-term loads. MCS computations are also performed and represent the “truth” system against which the efficiency and accuracy of the PCE surrogate model is assessed. Results suggest that the PCE approach requires significantly less effort to obtain comparable estimates to MCS.
@inproceedings{Nguyen:2018aa, address = {Madrid, Spain}, author = {Nguyen, Phong T. T. and Manuel, Lance and Coe, Ryan G.}, bibtex_show = true, booktitle = {Proceedings of the ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering}, date-added = {2020-10-07 14:22:26 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1115/OMAE2018-78766}, eprint = {https://asmedigitalcollection.asme.org/OMAE/proceedings-pdf/OMAE2018/51319/V010T09A035/2537032/v010t09a035-omae2018-78766.pdf}, month = jun, note = {V010T09A035}, series = {International Conference on Offshore Mechanics and Arctic Engineering}, title = {{On the Development of an Efficient Surrogate Model for Predicting Long-Term Extreme Loads on a Wave Energy Converter}}, url = {https://doi.org/10.1115/OMAE2018-78766}, volume = {10: Ocean Renewable Energy}, year = {2018}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2018-78766} } - Efficient wave tank assessment of WEC performanceGiorgio Bacelli, Steven J. Spencer, and Ryan G. CoeIn Proceedings of the 6th Marine Energy Technology Symposium (METS), Jun 2018
@inproceedings{Bacelli:2018ab, address = {Washington, D.C.}, author = {Bacelli, Giorgio and Spencer, Steven J. and Coe, Ryan G.}, bibtex_show = true, booktitle = {Proceedings of the 6th Marine Energy Technology Symposium (METS)}, date-added = {2020-10-07 14:20:39 -0600}, date-modified = {2025-08-20 18:22:59 -0600}, title = {Efficient wave tank assessment of {WEC} performance}, url = {https://www.osti.gov/servlets/purl/1506193}, year = {2018}, bdsk-url-1 = {https://www.osti.gov/servlets/purl/1506193} } - Feedback resonating control for a wave energy converterVictor Nevarez, Giorgio Bacelli, Ryan G. Coe, and David G. WilsonIn Proceedings of SPEEDAM2018, Jun 2018
Through the use of advanced control techniques, wave energy converters have significantly improved energy absorption. The motion of the WEC device is a significant contribution to the energy absorbed by the device. Reactive control (complex conjugate control) maximizes the energy absorption due to the impedance matching. The issue with complex conjugate control is that the controller is non-causal, which requires prediction into the oncoming waves to the device. This paper explores the potential of using system identification (SID) techniques to build a causal transfer function that approximates the complex conjugate controller over a specific frequency band of interest. The resulting controller is stable, and the average efficiency of the power captured by the causal controller is 99%, when compared to the non-causal complex conjugate.
@inproceedings{Nevarez:2018aa, address = {Amalfi, Italy}, author = {Nevarez, Victor and Bacelli, Giorgio and Coe, Ryan G. and Wilson, David G.}, bibtex_show = true, booktitle = {Proceedings of SPEEDAM2018}, date-added = {2020-10-07 12:59:01 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1109/SPEEDAM.2018.8445379}, groups = {AdvWecCntrls Pubs}, owner = {rcoe}, timestamp = {2019.01.31}, title = {Feedback resonating control for a wave energy converter}, url = {https://ieeexplore.ieee.org/document/8445379}, year = {2018}, bdsk-url-1 = {https://ieeexplore.ieee.org/document/8445379}, bdsk-url-2 = {https://doi.org/10.1109/SPEEDAM.2018.8445379} } - The Effect of Environmental Contour Selection on Expected Wave Energy Converter ResponseSamuel J. Edwards, and Ryan G. CoeJournal of Offshore Mechanics and Arctic Engineering, Aug 2018011901
A wave energy converter must be designed to both maximize power production and to ensure survivability, which requires the prediction of future sea states. It follows that precision in the prediction of those sea states should be important in determining a final WEC design. One common method used to estimate extreme conditions employs environmental contours of extreme conditions. This report compares five environmental contour methods and their repercussions on the response analysis of Reference Model 3 (RM3). The most extreme power take-off (PTO) force is predicted for the RM3 via each contour and compared to identify the potential difference in WEC response due to contour selection. The analysis provides insight into the relative performance of each of the contour methods and demonstrates the importance of an environmental contour in predicting extreme response. Ideally, over-predictions should be avoided, as they can add to device cost. At the same time, any “exceedances,” that is to say sea states that exceed predictions of the contour, should be avoided so that the device does not fail. For the extreme PTO force response studied here, relatively little sensitivity to the contour method is shown due to the collocation of the device’s resonance with a region of agreement between the contours. However, looking at the level of observed exceedances for each contour may still give a higher level of confidence to some methods.
@article{Edwards:2018aa, author = {Edwards, Samuel J. and Coe, Ryan G.}, bibtex_show = true, date-added = {2020-10-07 12:57:24 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1115/1.4040834}, eprint = {https://asmedigitalcollection.asme.org/offshoremechanics/article-pdf/141/1/011901/6375365/omae\_141\_01\_011901.pdf}, issn = {0892-7219}, journal = {Journal of Offshore Mechanics and Arctic Engineering}, month = aug, note = {011901}, number = {1}, title = {{The Effect of Environmental Contour Selection on Expected Wave Energy Converter Response}}, url = {https://doi.org/10.1115/1.4040834}, volume = {141}, year = {2018}, bdsk-url-1 = {https://doi.org/10.1115/1.4040834} } - Design Load Analysis for Wave Energy ConvertersJennifer Van Rij, Yi-Hsiang Yu, and Ryan G. CoeIn Proceedings of the ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering, Jun 2018V010T09A031
This study demonstrates a systematic methodology for establishing the design loads of a wave energy converter. The proposed design load methodology incorporates existing design guidelines, where they exist, and follows a typical design progression; namely, advancing from many, quick, order-of-magnitude accurate, conceptual stage design computations to a few, computationally intensive, high-fidelity, design validation simulations. The goal of the study is to streamline and document this process based on quantitative evaluations of the design loads’ accuracy at each design step and consideration for the computational efficiency of the entire design process. For the wave energy converter, loads, and site conditions considered, this study demonstrates an efficient and accurate methodology of evaluating the design loads.
@inproceedings{Van-Rij:2018aa, address = {Madrid, Spain}, author = {Van Rij, Jennifer and Yu, Yi-Hsiang and Coe, Ryan G.}, bibtex_show = true, booktitle = {Proceedings of the ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering}, date-added = {2020-10-07 12:51:32 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1115/OMAE2018-78178}, eprint = {https://asmedigitalcollection.asme.org/OMAE/proceedings-pdf/OMAE2018/51319/V010T09A031/2537197/v010t09a031-omae2018-78178.pdf}, month = jun, note = {V010T09A031}, series = {International Conference on Offshore Mechanics and Arctic Engineering}, title = {{Design Load Analysis for Wave Energy Converters}}, url = {https://doi.org/10.1115/OMAE2018-78178}, volume = {10: Ocean Renewable Energy}, year = {2018}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2018-78178} } - Full long-term design response analysis of a wave energy converterRyan G. Coe, Carlos Michelen, Aubrey Eckert-Gallup, and Cédric SallaberryRenewable Energy, Jun 2018
Efficient design of wave energy converters requires an accurate understanding of expected loads and responses during the deployment lifetime of a device. A study has been conducted to better understand best-practices for prediction of design responses in a wave energy converter. A case-study was performed in which a simplified wave energy converter was analyzed to predict several important device design responses. The application and performance of a full long-term analysis, in which numerical simulations were used to predict the device response for a large number of distinct sea states, was studied. Environmental characterization and selection of sea states for this analysis at the intended deployment site were performed using principle-components analysis. The full long-term analysis applied here was shown to be stable when implemented with a relatively low number of sea states and convergent with an increasing number of sea states. As the number of sea states utilized in the analysis was increased, predicted response levels did not change appreciably. However, uncertainty in the response levels was reduced as more sea states were utilized.
@article{Coe:2018aa, author = {Coe, Ryan G. and Michelen, Carlos and Eckert-Gallup, Aubrey and Sallaberry, C{\'e}dric}, bibtex_show = true, date-added = {2020-10-07 12:49:13 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1016/j.renene.2017.09.056}, issn = {0960-1481}, journal = {Renewable Energy}, keywords = {Wave energy, Extreme conditions, Design load, Long-term response}, pages = {356 - 366}, title = {Full long-term design response analysis of a wave energy converter}, url = {http://www.sciencedirect.com/science/article/pii/S0960148117309187}, volume = {116}, year = {2018}, bdsk-url-1 = {http://www.sciencedirect.com/science/article/pii/S0960148117309187}, bdsk-url-2 = {https://doi.org/10.1016/j.renene.2017.09.056} } - Alternative approaches to develop environmental contours from metocean dataLance Manuel, Phong T. T. Nguyen, Jarred Canning, Ryan G. Coe, Aubrey C. Eckert-Gallup, and Nevin MartinJournal of Ocean Engineering and Marine Energy, Jun 2018
It is necessary to evaluate site-specific extreme environmental conditions in the design of wave energy converters (WECs) as well as other offshore structures. As WECs are generally resonance-driven devices, critical metocean parameters associated with a target return period of interest (e.g., 50 years) must generally be established using combinations, say, of significant wave height and spectral peak period, as opposed to identifying single-valued wave height levels alone. We present several methods for developing so-called “environmental contours”for any target return period. The environmental contour (EC) method has been widely acknowledged as an efficient way to derive design loads for offshore oil and gas platforms and for land-based as well as offshore wind turbines. The use of this method for WECs is also being considered. A challenge associated with its use relates to the need to accurately characterize the uncertainties in metocean variables that define the “environment”. The joint occurrence frequency of values of two or more random variables needs to be defined formally. There are many ways this can be done—the most thorough and complete of these is to define a multivariate joint probability distribution of the random variables. However, challenges arise when data from the site where the WEC device is to be deployed are limited, making it difficult to estimate the joint probability distribution. A more easily estimated set of inputs consists of marginal distribution functions for each random variable and pairwise correlation coefficients. Pearson correlation coefficients convey information that rely on up to the second moment of each variable and on the expected value of the product of the paired variables. Kendall’s rank correlation coefficients, on the other hand, convey information on similarity in the “rank”of two variables and are useful especially in dealing with extreme values. The EC method is easily used with Rosenblatt transformations when joint distributions are available. In cases where Pearson’s correlation coefficients have been estimated along with marginal distributions, a Nataf transformation can be used, and if Kendall’s rank coefficients have been estimated and are available, a copula-based transformation can be used. We demonstrate the derivation of 50-year sea state parameters using the EC method with all three approaches where we consider data from the National Data Buoy Center Station 46022 (which can be considered the site for potential WEC deployment). A comparison of the derived environmental contours using the three approaches is presented. The focus of this study is on investigating differences between the derived environmental contours and, thus, on associated sea states arising from the different dependence structure assumptions for the metocean random variables. Both parametric and non-parametric approaches are used to define the probability distributions.
@article{Manuel:2018aa, author = {Manuel, Lance and Nguyen, Phong T. T. and Canning, Jarred and Coe, Ryan G. and Eckert-Gallup, Aubrey C. and Martin, Nevin}, bibtex_show = true, da = {2018/11/01}, date-added = {2020-10-07 12:44:32 -0600}, date-modified = {2020-10-07 12:44:32 -0600}, doi = {10.1007/s40722-018-0123-0}, id = {Manuel2018}, isbn = {2198-6452}, journal = {Journal of Ocean Engineering and Marine Energy}, number = {4}, pages = {293--310}, title = {Alternative approaches to develop environmental contours from metocean data}, ty = {JOUR}, url = {https://doi.org/10.1007/s40722-018-0123-0}, volume = {4}, year = {2018}, bdsk-url-1 = {https://doi.org/10.1007/s40722-018-0123-0} } - Control of Three Degrees-of-Freedom Wave Energy Converters Using Pseudo-Spectral MethodsOssama Abdelkhalik, Shangyan Zou, Rush Robinett, Giorgio Bacelli, David Wilson, and Ryan CoeJournal of Dynamic Systems, Measurement, and Control, Jan 2018
@article{Abdelkhalik:2018aa, annote = {10.1115/1.4038860}, author = {Abdelkhalik, Ossama and Zou, Shangyan and Robinett, Rush and Bacelli, Giorgio and Wilson, David and Coe, Ryan}, bibtex_show = true, date = {2018/01/19}, date-added = {2020-10-07 12:39:06 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1115/1.4038860}, groups = {AdvWecCntrls Pubs}, isbn = {0022-0434}, journal = {Journal of Dynamic Systems, Measurement, and Control}, m3 = {doi: 10.1115/1.4038860}, month = jan, n2 = {This paper presents a solution to the optimal control problem of a three degrees-of-freedom (3DOF) wave energy converter (WEC). The three modes are the heave, pitch, and surge. The dynamic model is characterized by a coupling between the pitch and surge modes, while the heave is decoupled. The heave, however, excites the pitch motion through nonlinear parametric excitation in the pitch mode. This paper uses Fourier series (FS) as basis functions to approximate the states and the control. A simplified model is first used where the parametric excitation term is neglected and a closed-form solution for the optimal control is developed. For the parametrically excited case, a sequential quadratic programming approach is implemented to solve for the optimal control numerically. Numerical results show that the harvested energy from three modes is greater than three times the harvested energy from the heave mode alone. Moreover, the harvested energy using a control that accounts for the parametric excitation is significantly higher than the energy harvested when neglecting this nonlinear parametric excitation term.}, number = {7}, pages = {074501--074501-9}, publisher = {ASME}, title = {Control of Three Degrees-of-Freedom Wave Energy Converters Using Pseudo-Spectral Methods}, ty = {JOUR}, url = {http://dx.doi.org/10.1115/1.4038860}, volume = {140}, year = {2018}, bdsk-url-1 = {http://dx.doi.org/10.1115/1.4038860} } - Linear and Nonlinear System Identification of a Wave Energy ConverterHancheol Cho, Giorgio Bacelli, and Ryan G CoeIn Proceedings of the 4th Marine Energy Technology Symposium (METS2016), Jan 2018
@inproceedings{Cho:2018aa, address = {Washington, D.C.}, author = {Cho, Hancheol and Bacelli, Giorgio and Coe, Ryan G}, bibtex_show = true, booktitle = {Proceedings of the 4th {Marine} {Energy} {Technology} {Symposium} (METS2016)}, date-added = {2020-10-07 12:35:46 -0600}, date-modified = {2025-08-20 18:28:26 -0600}, groups = {AdvWecCntrls Pubs}, owner = {rcoe}, timestamp = {2018.09.18}, title = {Linear and Nonlinear System Identification of a Wave Energy Converter}, url = {https://www.osti.gov/servlets/purl/1506194}, year = {2018}, bdsk-url-1 = {https://www.osti.gov/servlets/purl/1506194} } - Classification systems for wave energy resources and WEC technologiesVincent S. Neary, Ryan G. Coe, João Cruz, Kevin Haas, Giorgio Bacelli, Yannick Debruyne, Seongho Ahn, and Victor NevarezInternational Marine Energy Journal, Nov 2018
@article{Neary:2018aa, author = {Neary, Vincent S. and Coe, Ryan G. and Cruz, Jo{\~a}o and Haas, Kevin and Bacelli, Giorgio and Debruyne, Yannick and Ahn, Seongho and Nevarez, Victor}, bibtex_show = true, date-added = {2020-10-07 12:35:34 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.36688/imej.1.71-79}, journal = {International Marine Energy Journal}, month = nov, number = {2}, pages = {71--79}, title = {Classification systems for wave energy resources and {WEC} technologies}, url = {https://marineenergyjournal.org/imej/article/view/29}, volume = {1}, year = {2018}, bdsk-url-1 = {https://marineenergyjournal.org/imej/article/view/29}, bdsk-url-2 = {https://doi.org/10.36688/imej.1.71-79} } - Initial results from wave tank test of closed-loop WEC controlRyan G. Coe, Giorgio Bacelli, Steven J. Spencer, and Hancheol ChoNov 2018
@techreport{Coe:2018ac, address = {Albuquerque, NM}, author = {Coe, Ryan G. and Bacelli, Giorgio and Spencer, Steven J. and Cho, Hancheol}, bibtex_show = true, date = {2018-11-07}, date-added = {2020-10-07 12:35:05 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.2172/1531328}, groups = {AdvWecCntrls Pubs}, institution = {Sandia National Laboratories}, month = nov, number = {SAND2018-12858}, owner = {rcoe}, timestamp = {2019.01.03}, title = {Initial results from wave tank test of closed-loop {WEC} control}, url = {https://doi.org/10.2172/1531328}, year = {2018}, bdsk-url-1 = {https://www.osti.gov/biblio/1531328-initial-results-from-wave-tank-test-closed-loop-wec-control}, bdsk-url-2 = {https://doi.org/10.2172/1531328} } - A comparative study on wave prediction for WECsRyan G. Coe, Giorgio Bacelli, Victor Nevarez, Hancheol Cho, and Felipe Wilches-BernalNov 2018
@techreport{Coe:2018ab, address = {Albuquerque, NM}, author = {Coe, Ryan G. and Bacelli, Giorgio and Nevarez, Victor and Cho, Hancheol and Wilches-Bernal, Felipe}, bibtex_show = true, date-added = {2020-10-07 12:35:05 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.2172/1476166}, groups = {AdvWecCntrls Pubs}, institution = {Sandia National Laboratories}, number = {SAND2018-10945}, title = {A comparative study on wave prediction for {WECs}}, url = {https://www.osti.gov/biblio/1476166}, year = {2018}, bdsk-url-1 = {https://www.osti.gov/biblio/1476166-comparative-study-wave-prediction-wecs}, bdsk-url-2 = {https://doi.org/10.2172/1476166} }
2017
- WEC Extreme Conditions Modeling Sandia Summer Intern 2017 ReportJarred Canning, Samuel Edwards, Tyler Richard Esterly, Bibiana Elisabeth Seng, Laura Smith, Zacharia William Stuart, Aubrey Celia Eckert, Nevin Martin, and Ryan G. CoeSep 2017
@techreport{Canning:2017aa, address = {Albuquerque, NM}, author = {Canning, Jarred and Edwards, Samuel and Esterly, Tyler Richard and Seng, Bibiana Elisabeth and Smith, Laura and Stuart, Zacharia William and Eckert, Aubrey Celia and Martin, Nevin and Coe, Ryan G.}, bibtex_show = true, date-added = {2020-10-07 14:29:34 -0600}, date-modified = {2025-07-03 12:44:42 -0600}, doi = {10.2172/1596200}, institution = {Sandia National Laboratories}, month = sep, number = {SAND2017-10592}, title = {{WEC} Extreme Conditions Modeling Sandia Summer Intern 2017 Report}, url = {https://www.osti.gov/biblio/1596200}, year = {2017}, bdsk-url-1 = {https://www.osti.gov/biblio/1596200-wec-extreme-conditions-modeling-sandia-summer-intern-report}, bdsk-url-2 = {https://doi.org/10.2172/1596200} } - A Survey of WEC Reliability, Survival and Design PracticesRyan G. Coe, Yi-Hsiang Yu, and Jennifer Van RijEnergies, Dec 2017
A wave energy converter must be designed to survive and function efficiently, often in highly energetic ocean environments. This represents a challenging engineering problem, comprising systematic failure mode analysis, environmental characterization, modeling, experimental testing, fatigue and extreme response analysis. While, when compared with other ocean systems such as ships and offshore platforms, there is relatively little experience in wave energy converter design, a great deal of recent work has been done within these various areas. This paper summarizes the general stages and workflow for wave energy converter design, relying on supporting articles to provide insight. By surveying published work on wave energy converter survival and design response analyses, this paper seeks to provide the reader with an understanding of the different components of this process and the range of methodologies that can be brought to bear. In this way, the reader is provided with a large set of tools to perform design response analyses on wave energy converters.
@article{Coe:2017ac, author = {Coe, Ryan G. and Yu, Yi-Hsiang and Rij, Jennifer Van}, bibtex_show = true, date-added = {2020-10-07 14:18:44 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.3390/en11010004}, issn = {1996-1073}, journal = {Energies}, month = dec, number = {1}, pages = {4}, publisher = {MDPI AG}, title = {A Survey of {WEC} Reliability, Survival and Design Practices}, url = {http://dx.doi.org/10.3390/en11010004}, volume = {11}, year = {2017}, bdsk-url-1 = {http://dx.doi.org/10.3390/en11010004} } - On the Long-Term Reliability Analysis of a Point Absorber Wave Energy ConverterJarred Canning, Phong Nguyen, Lance Manuel, and Ryan G. CoeIn Proceedings of the ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering, Jun 2017V010T09A024
Of interest in this study is the long-term response and performance of a two-body wave point absorber (“Reference Model 3”), which serves as a wave energy converter (WEC). In a previous study, the short-term uncertainty in this device’s response was studied for an extreme sea state. We now focus on the assessment of the long-term response of the device where we consider all possible sea states at a site of interest. We demonstrate how simulation tools may be used to evaluate the long-term response and consider key performance parameters of the WEC device, which are the heave and surge forces on the power take-off system and the power take-off extension. We employ environmental data at a designated deployment site in Northern California. Metocean information is generated using approximately 15 years of data from this site (National Data Buoy Center site no. 46022). For various sea states, a selected significant wave height and peak period are chosen to describe representative conditions. Then, using a public-domain simulation tool (Wave Energy Converter Simulator or WEC-Sim), we generate various short-term time-domain response measure for these sea states. Distribution fits to extreme response statistics are generated, for each bin that represents a cluster of sea states, using the open-source toolbox, WDRT (WEC Design Response Toolbox). Long-term distributions for each response variable of interest are estimated by weighting short-term distributions by the likelihood of the sea states; from these distributions, the 50-year response can be derived. The 50-year response is also estimated using an approximate but more efficient inverse reliability approach. Comparisons are made between the two approaches.
@inproceedings{Canning:2017ab, address = {Trondheim, Norway}, author = {Canning, Jarred and Nguyen, Phong and Manuel, Lance and Coe, Ryan G.}, bibtex_show = true, booktitle = {Proceedings of the ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering}, date-added = {2020-10-07 12:58:46 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1115/OMAE2017-62141}, eprint = {https://asmedigitalcollection.asme.org/OMAE/proceedings-pdf/OMAE2017/57786/V010T09A024/2534932/v010t09a024-omae2017-62141.pdf}, month = jun, note = {V010T09A024}, series = {International Conference on Offshore Mechanics and Arctic Engineering}, title = {{On the Long-Term Reliability Analysis of a Point Absorber Wave Energy Converter}}, url = {https://doi.org/10.1115/OMAE2017-62141}, volume = {10: Ocean Renewable Energy}, year = {2017}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2017-62141} } - Model Predictive Control of parametric excited pitch-surge modes in wave energy convertersShangyan Zou, Ossama Abdelkhalik, Rush Robinett, Umesh Korde, Giorgio Bacelli, David Wilson, and Ryan CoeInternational Journal of Marine Energy, Jun 2017
For a heave-pitch-surge three-degrees-of-freedom wave energy converter, the heave mode is usually decoupled from the pitch-surge modes for small motions. The pitch-surge modes are usually coupled and are parametrically excited by the heave mode, depending on the buoy geometry. In this paper, a Model Predictive Control is applied to the parametric excited pitch-surge motion, while the heave motion is optimized independently. The optimality conditions are derived, and a gradient-based numerical optimization algorithm is used to search for the optimal control. Numerical tests are conducted for regular and Bretschneider waves. The results demonstrate that the proposed control can be implemented to harvest more than three times the energy that can be harvested using a heave-only wave energy converter. The energy harvested using a parametrically excited model is higher than that is harvested when using a linear model.
@article{Zou:2017aa, author = {Zou, Shangyan and Abdelkhalik, Ossama and Robinett, Rush and Korde, Umesh and Bacelli, Giorgio and Wilson, David and Coe, Ryan}, bibtex_show = true, date-added = {2020-10-07 12:49:39 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1016/j.ijome.2017.05.002}, groups = {AdvWecCntrls Pubs, [rcoe:]}, issn = {2214-1669}, journal = {International Journal of Marine Energy}, keywords = {Wave energy conversion, Parametric excited wave energy conversion, Pitch-surge control, Model Predictive Control}, owner = {rcoe}, pages = {32 - 46}, timestamp = {2017.06.12}, title = {Model Predictive Control of parametric excited pitch-surge modes in wave energy converters}, url = {http://www.sciencedirect.com/science/article/pii/S2214166917300504}, volume = {19}, year = {2017}, bdsk-url-1 = {http://www.sciencedirect.com/science/article/pii/S2214166917300504}, bdsk-url-2 = {https://doi.org/10.1016/j.ijome.2017.05.002} } - A competition for WEC control systemsJohn Ringwood, Francesco Ferri, Kelley M Ruehl, Yi-Hsiang Yu, Ryan G. Coe, Giorgio Bacelli, Jochem Weber, and Morten KramerIn Proceedings of the 12th European Wave and Tidal Energy Conference (EWTEC2017), Jun 2017
This paper outlines a proposed open competition which will compare energy-maximising controllers for wave energy converters (WECs), both in simulation, and in real time, using a scale device in a tank test situation. To date, a wide variety of WEC control algorithms have been proposed, but have been difficult to compare due to differences in the simulation/scale models they are evaluated on, the range of incident sea states employed, and the reliance to a greater or lesser extent on wave or excitation force forecasts. In addition, most WEC control algorithms have been evaluated only in simulation, which masks the real-time computational capability, as well as the degree to which the model-based controllers are robust to WEC modelling errors, since the controllers are predominantly evaluated with a WEC simulation model identical to that upon which the controller is based. This paper describes the format of a proposed WEC control competition, detailing the scale target device, the open-source WEC-Sim simulation platform, along with likely performance metrics and range of sea states under which the assessment will be performed. The paper serves the purpose both as an announcement of the competition and indicates the nominal schedule, as well as soliciting feedback at this stage of the process.
@inproceedings{Ringwood:2017aa, address = {Cork, Ireland}, author = {Ringwood, John and Ferri, Francesco and Ruehl, Kelley M and Yu, Yi-Hsiang and Coe, Ryan G. and Bacelli, Giorgio and Weber, Jochem and Kramer, Morten}, bibtex_show = true, booktitle = {Proceedings of the 12th European Wave and Tidal Energy Conference (EWTEC2017)}, date-added = {2020-10-07 12:47:29 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, number = {831}, pages = {1--9}, title = {A competition for {WEC} control systems}, url = {https://tethys-engineering.pnnl.gov/sites/default/files/publications/Ringwoodetal2017.pdf}, year = {2017}, bdsk-url-1 = {https://tethys-engineering.pnnl.gov/sites/default/files/publications/Ringwoodetal2017.pdf} } - WEC geometry optimization with advanced controlOssama Abdelkhalik, Ryan G. Coe, Giorgio Bacelli, and David G. WilsonIn International Conference on Ocean, Offshore and Arctic Engineering (OMAE2017), Jun 2017
A study was performed to optimize the geometry of a point absorber style wave energy converter (WEC). An axisymmetric single-body device, moving in heave only, was considered. Design geometries, generated using a parametric definition, were optimized using genetic algorithms. Each geometry was analyzed using a boundary element model (BEM) tool to obtain corresponding frequency domain models. Based on these models, a pseudo-spectral method was applied to develop a control methodology for each geometry. The performance of each design was assessed using a Bretschneider sea state. The objective of optimization is to maximize harvested energy. In this preliminary investigation, a constraint is imposed on the the geometry to guarantee a linear dynamic model would be valid for all geometries generated by the optimization tool. Numerical results are presented for axisymmetric buoy shapes.
@inproceedings{Abdelkhalik:2017ab, author = {Abdelkhalik, Ossama and Coe, Ryan G. and Bacelli, Giorgio and Wilson, David G.}, bibtex_show = true, booktitle = {International Conference on Ocean, Offshore and Arctic Engineering (OMAE2017)}, date-added = {2020-10-07 12:39:01 -0600}, date-modified = {2025-08-20 18:30:16 -0600}, doi = {10.1115/OMAE2017-61917}, file = {Abdelkhalik2017.pdf:Abdelkhalik2017.pdf:PDF}, groups = {AdvWecCntrls Pubs, Design optimization}, organization = {Trondheim, Norway}, owner = {rcoe}, publisher = {ASME}, timestamp = {2016.11.23}, title = {{WEC} geometry optimization with advanced control}, url = {https://doi.org/10.1115/OMAE2017-61917}, volume = {10: Ocean Renewable Energy}, year = {2017}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2017-61917} } - Multi Resonant Feedback Control of Three-Degree-of-Freedom Wave Energy ConvertersIEEE Transactions on Sustainable Energy, Jun 2017
or a three-degree-of-freedom wave energy converter (heave, pitch, and surge), the equations of motion could be coupled depending on the buoy shape.or a three-degree-offreedom wave energy converter (heave, pitch, and surge), the equations of motion could be coupled depending on the buoy shape.F This paper presents a multi-resonant feedback control, in a general framework, for this type of a wave energy converter that is modeled by linear time invariant dynamic systems. The proposed control strategy finds the optimal control in the sense that it computes the control based on the complex conjugate criteria. This control strategy is relatively easy to implement since it is a feedback control in the time domain that requires only measurements of the buoy motion. Numerical tests are presented for two different buoy shapes: a sphere and a cylinder. Regular, Bretschnieder, and Ochi-Hubble waves are tested. Simulation results show that the proposed controller harvests energy in the pith-surge-heave modes that is about three times the energy that can be harvested using a heave only device. This multi resonant control can also be used to shift the energy harvesting between the coupled modes which can be exploited to eliminate one of the actuators while maintaining about the same level of energy harvesting.
@article{Abdelkhalik:2017aa, author = {Abdelkhalik, O. and Zou, S. and III, R. Robinett and Bacelli, G. and Wilson, D. and Coe, R. and Korde, U. A.}, bibtex_show = true, date-added = {2020-10-07 12:38:55 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1109/TSTE.2017.2692647}, groups = {AdvWecCntrls Pubs}, issn = {1949-3029}, journal = {IEEE Transactions on Sustainable Energy}, keywords = {Actuators;Damping;Energy harvesting;Gravity;Mathematical model;Surges;Multi Resonant Control;Three Degrees of Freedom WEC;Wave Energy Conversion,}, number = {99}, owner = {rcoe}, pages = {1-1}, title = {Multi Resonant Feedback Control of Three-Degree-of-Freedom Wave Energy Converters}, url = {http://ieeexplore.ieee.org/document/7895127/}, volume = {PP}, year = {2017}, bdsk-url-1 = {http://ieeexplore.ieee.org/document/7895127/}, bdsk-url-2 = {https://doi.org/10.1109/TSTE.2017.2692647} } - System Identification of a Heaving Point Absorber: Design of Experiment and Device ModelingGiorgio Bacelli, Ryan G. Coe, David Patterson, and David WilsonEnergies, Jun 2017
Empirically based modeling is an essential aspect of design for a wave energy converter. Empirically based models are used in structural, mechanical and control design processes, as well as for performance prediction. Both the design of experiments and methods used in system identification have a strong impact on the quality of the resulting model. This study considers the system identification and model validation process based on data collected from a wave tank test of a model-scale wave energy converter. Experimental design and data processing techniques based on general system identification procedures are discussed and compared with the practices often followed for wave tank testing. The general system identification processes are shown to have a number of advantages, including an increased signal-to-noise ratio, reduced experimental time and higher frequency resolution. The experimental wave tank data is used to produce multiple models using different formulations to represent the dynamics of the wave energy converter. These models are validated and their performance is compared against one another. While most models of wave energy converters use a formulation with surface elevation as an input, this study shows that a model using a hull pressure measurement to incorporate the wave excitation phenomenon has better accuracy.
@article{Bacelli:2017aa, author = {Bacelli, Giorgio and Coe, Ryan G. and Patterson, David and Wilson, David}, bibtex_show = true, date-added = {2020-10-07 12:37:21 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.3390/en10040472}, file = {Bacelli2017a.pdf:pdfs\\Bacelli2017a.pdf:PDF;Bacelli2017a.pdf:.\\pdfs\\Bacelli2017a.pdf:PDF}, groups = {AdvWecCntrls Pubs, SID}, issn = {1996-1073}, issue = {4}, journal = {Energies}, number = {10}, owner = {rcoe}, pages = {472}, publisher = {Multidisciplinary Digital Publishing Institute}, timestamp = {2017.02.19}, title = {System Identification of a Heaving Point Absorber: Design of Experiment and Device Modeling}, url = {http://www.mdpi.com/1996-1073/10/4/472}, volume = {10}, year = {2017}, bdsk-url-1 = {http://www.mdpi.com/1996-1073/10/4/472}, bdsk-url-2 = {https://doi.org/10.3390/en10040472} } - Design and Bench Testing of a Model-Scale WEC for Advanced PTO Control ResearchGiorgio Bacelli, Steven J. Spencer, Ryan G. Coe, Anirban Mazumdar, David Patterson, and Kevin DulleaIn European Wave and Tidal Energy Conference (EWTEC2017), Jun 2017
@inproceedings{Bacelli:2017ab, address = {Cork, Ireland}, author = {Bacelli, Giorgio and Spencer, Steven J. and Coe, Ryan G. and Mazumdar, Anirban and Patterson, David and Dullea, Kevin}, bibtex_show = true, booktitle = {European Wave and Tidal Energy Conference (EWTEC2017)}, date-added = {2020-10-07 12:37:21 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, groups = {AdvWecCntrls Pubs}, owner = {rcoe}, timestamp = {2017.03.26}, title = {Design and Bench Testing of a Model-Scale {WEC} for Advanced {PTO} Control Research}, url = {https://prod-ng.sandia.gov/techlib-noauth/access-control.cgi/2017/170523a.pdf}, year = {2017}, bdsk-url-1 = {https://prod-ng.sandia.gov/techlib-noauth/access-control.cgi/2017/170523a.pdf} } - WEC System Identification and Model ValidationGiorgio Bacelli, and Ryan G. CoeIn Proceedings of the 5th Marine Energy Technology Symposium (METS2017), Jun 2017
@inproceedings{Bacelli:2017ac, address = {Washington, D.C.}, author = {Bacelli, Giorgio and Coe, Ryan G.}, bibtex_show = true, booktitle = {Proceedings of the 5th {Marine} {Energy} {Technology} {Symposium} (METS2017)}, date-added = {2020-10-07 12:37:21 -0600}, date-modified = {2025-08-20 18:32:25 -0600}, file = {Bacelli2017d.pdf:Bacelli2017d.pdf:PDF}, groups = {SID, AdvWecCntrls Pubs}, owner = {rcoe}, timestamp = {2017.04.10}, title = {{WEC} System Identification and Model Validation}, url = {https://www.osti.gov/biblio/1648709-wec-system-identification-model-validation}, year = {2017}, bdsk-url-1 = {https://www.osti.gov/biblio/1648709-wec-system-identification-model-validation} } - State estimation for wave energy convertersGiorgio Bacelli, and Ryan G. CoeApr 2017
This report gives a brief discussion and examples on the topic of state estimation for wave energy converters (WECs). These methods are intended for use to enable real-time closed loop control of WECs.
@techreport{Bacelli:2017ad, address = {Albuquerque, NM}, author = {Bacelli, Giorgio and Coe, Ryan G.}, bibtex_show = true, date-added = {2020-10-07 12:37:21 -0600}, date-modified = {2025-08-21 12:48:19 -0600}, doi = {10.2172/1365524}, groups = {AdvWecCntrls Pubs}, institution = {Sandia National Laboratories}, month = apr, number = {SAND2017-4401}, owner = {rcoe}, timestamp = {2017.08.24}, title = {State estimation for wave energy converters}, url = {https://www.osti.gov/biblio/1365524}, year = {2017}, bdsk-url-1 = {https://mhkdr.openei.org/files/212/SAND2017-4401.pdf}, bdsk-url-2 = {https://doi.org/10.2172/1365524} } - Classification Systems for Wave Energy Resources and WEC TechnologiesVincent S. Neary, Ryan G. Coe, João Cruz, Kevin Haas, Giorgio Bacelli, Yannick Debruyne, Seongho Ahn, and Victor NevarezIn European Wave and Tidal Energy Conference (EWTEC2017), Apr 2017
@inproceedings{Neary:2017aa, address = {Cork, Ireland}, author = {Neary, Vincent S. and Coe, Ryan G. and Cruz, Jo{\~a}o and Haas, Kevin and Bacelli, Giorgio and Debruyne, Yannick and Ahn, Seongho and Nevarez, Victor}, bibtex_show = true, booktitle = {European Wave and Tidal Energy Conference (EWTEC2017)}, date-added = {2020-10-07 12:35:34 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, file = {Neary2017.pdf:Neary2017.pdf:PDF}, groups = {AdvWecCntrls Pubs}, owner = {rcoe}, timestamp = {2017.08.16}, title = {Classification Systems for Wave Energy Resources and {WEC} Technologies}, url = {https://www.osti.gov/biblio/1464892-classification-systems-wave-energy-resources-wec-technologies}, year = {2017}, bdsk-url-1 = {https://www.osti.gov/biblio/1464892-classification-systems-wave-energy-resources-wec-technologies} } - An assessment of WEC control performance uncertaintyRyan G. Coe, G Bacelli, O Abdelkhalik, and DG WilsonIn International Conference on Ocean, Offshore and Arctic Engineering (OMAE2017), Apr 2017
A linear dynamic model for a wave energy converter (WEC) has been developed based on the results of experimental wave tank testing. Based on this model, a model predictive control (MPC) strategy has been designed and implemented. To assess the performance of this control strategy, a deployment environment off the coast of Newport, OR has been selected and the controller has been used to simulate the WEC response in a set of irregular sea states. To better understand the influence of model accuracy on control performance, an uncertainty analysis has been performed by varying the parameters of the model used for the design of the controller (i.e. the control model), while keeping the WEC dynamic model employed in these simulations (i.e. the plant model) unaltered. The results of this study indicate a relative low sensitivity of the MPC control strategy to uncertainties in the controller model for the specific case studied here.
@inproceedings{Coe:2017ab, address = {Trondheim, Norway}, author = {Coe, Ryan G. and Bacelli, G and Abdelkhalik, O and Wilson, DG}, bibtex_show = true, booktitle = {International Conference on Ocean, Offshore and Arctic Engineering (OMAE2017)}, date-added = {2020-10-07 12:35:05 -0600}, date-modified = {2025-08-21 12:46:54 -0600}, doi = {10.1115/OMAE2017-61912}, file = {Coe2017.pdf:Coe2017.pdf:PDF}, groups = {AdvWecCntrls Pubs}, owner = {rcoe}, publisher = {ASME}, timestamp = {2016.11.23}, title = {An assessment of {WEC} control performance uncertainty}, url = {https://doi.org/10.1115/OMAE2017-61912}, volume = {10: Ocean Renewable Energy}, year = {2017}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2017-61912} } - A comparison of control strategies for wave energy convertersRyan G. Coe, Giorgio Bacelli, David G. Wilson, Ossama Abdelkhalik, Umesh A. Korde, and Rush D. Robinett IIIInternational Journal of Marine Energy, Apr 2017
In this study, we employ a numerical model to compare the performance of a number of wave energy converter control strategies. The controllers selected for evaluation span a wide range in their requirements for implementation. Each control strategy is evaluated using a single numerical model with a set of sea states to represent a deployment site off the coast of Newport, OR. A number of metrics, ranging from power absorption to kinematics, are employed to provide a comparison of each control strategy’s performance that accounts for both relative benefits and costs. The results show a wide range of performances from the different controllers and highlight the need for a holistic design approach which considers control design as a parallel component within the larger process WEC design.
@article{Coe:2017aa, author = {Coe, Ryan G. and Bacelli, Giorgio and Wilson, David G. and Abdelkhalik, Ossama and Korde, Umesh A. and III, Rush D. Robinett}, bibtex_show = true, date-added = {2020-10-07 12:35:05 -0600}, date-modified = {2025-08-21 12:47:26 -0600}, doi = {10.1016/j.ijome.2017.11.001}, groups = {AdvWecCntrls Pubs}, issn = {2214-1669}, journal = {International Journal of Marine Energy}, keywords = {Wave energy, Control, Dynamics}, number = {Supplement C}, pages = {45 - 63}, title = {A comparison of control strategies for wave energy converters}, url = {http://www.sciencedirect.com/science/article/pii/S2214166917300905}, volume = {20}, year = {2017}, bdsk-url-1 = {http://www.sciencedirect.com/science/article/pii/S2214166917300905}, bdsk-url-2 = {https://doi.org/10.1016/j.ijome.2017.11.001} }
2016
- On the short-term uncertainty in performance of a point absorber wave energy converterLance Manuel, Jarred Canning, Ryan G. Coe, and Carlos MichelenIn Proceedings of the 4th Marine Energy Technology Symposium (METS), Apr 2016
Of interest, in this study, is the quantification of uncertainty in the performance of a two-body wave point absorber (Reference Model 3 or RM3), which serves as a wave energy converter (WEC). We demonstrate how simulation tools may be used to establish short-term relationships between any performance parameter of the WEC device and wave height in individual sea states. We demonstrate this methodology for two sea states. Efficient structural reliability methods, validated using more expensive Monte Carlo sampling, allow the estimation of uncertainty in performance of the device. Such methods, when combined with metocean data quantifying the likelihood of different sea states, can be useful in long-term studies and in reliability-based design.
@inproceedings{Manuel:2016aa, address = {Washington, D.C.}, author = {Manuel, Lance and Canning, Jarred and Coe, Ryan G. and Michelen, Carlos}, bibtex_show = true, booktitle = {Proceedings of the 4th Marine Energy Technology Symposium (METS)}, date-added = {2020-10-07 14:37:13 -0600}, date-modified = {2025-08-20 18:36:29 -0600}, title = {On the short-term uncertainty in performance of a point absorber wave energy converter}, url = {https://www.osti.gov/servlets/purl/1366659}, year = {2016}, bdsk-url-1 = {https://www.osti.gov/servlets/purl/1366659} } - Tool for Distributed Pressure Time-Histories of Marine Structures: Verification and Case Study With a WECCarlos Michelen, Ryan G. Coe, Yi-Hsiang Yu, and Qi WangIn Proceedings of the 4th Marine Energy Technology Symposium (METS2016), Mar 2016
In this paper we describe the theory and code implementation of a tool to obtain the time-dependent pressure distribution on a marine structure using the results from a boundary element method code (BEM). Here, we present a case study of a floating wave energy converter (WEC) in regular waves. The results are verified by comparison with open-source codes and then used to run a structural simulation (finite element analysis) to showcase a possible application.
@inproceedings{Michelen:2016aa, address = {Washington DC}, author = {Michelen, Carlos and Coe, Ryan G. and Yu, Yi-Hsiang and Wang, Qi}, bibtex_show = true, booktitle = {Proceedings of the 4th {Marine} {Energy} {Technology} {Symposium} (METS2016)}, date-added = {2020-10-07 13:02:26 -0600}, date-modified = {2025-08-20 18:37:53 -0600}, month = mar, title = {Tool for Distributed Pressure Time-Histories of Marine Structures: Verification and Case Study With a {WEC}}, url = {https://www.osti.gov/biblio/1618220-tool-distributed-pressure-time-histories-marine-structures-verification-case-study-wec}, year = {2016}, bdsk-url-1 = {https://www.osti.gov/biblio/1618220-tool-distributed-pressure-time-histories-marine-structures-verification-case-study-wec} } - WDRT: A toolbox for design-response analysis of wave energy convertersRyan G. Coe, Carlos Michelen, Aubrey Celia Eckert-Gallup, Yi-Hsiang Yu, and Jennifer Van RijIn Proceedings of the 4th Marine Energy Technology Symposium (METS), Mar 2016
In this paper, we present a numerical toolbox for design-response analysis of wave energy converters (WECs). The “WEC Design Response Toolbox (WDRT)” was developed during a series of efforts to better understand and improved the WEC survival design process. The WDRT has been designed as a tool for researchers and developers, enabling the straightforward application of statistical and engineering methods needed for design response analysis of a WEC, including characterization of environmental extremes, extreme response statistics, fatigue analysis and design wave composition. This paper gives a brief overview of the WDRT including its capabilities and underlying theory.
@inproceedings{Coe:2016aa, address = {Washington DC}, author = {Coe, Ryan G. and Michelen, Carlos and Eckert-Gallup, Aubrey Celia and Yu, Yi-Hsiang and Van Rij, Jennifer}, bibtex_show = true, booktitle = {Proceedings of the 4th Marine Energy Technology Symposium (METS)}, date-added = {2020-10-07 12:45:09 -0600}, date-modified = {2025-08-20 18:39:57 -0600}, institution = {Sandia National Lab.(SNL-NM), Albuquerque, NM (United States)}, number = {SAND2016-2983C}, title = {{WDRT}: A toolbox for design-response analysis of wave energy converters}, url = {https://www.osti.gov/biblio/1366660}, year = {2016}, bdsk-url-1 = {https://www.osti.gov/biblio/1366660} } - On the control design of wave energy converters with wave predictionOssama Abdelkhalik, Rush Robinett, Shangyan Zou, Giorgio Bacelli, Ryan Coe, Diana Bull, David Wilson, and Umesh KordeJournal of Ocean Engineering and Marine Energy, Mar 2016
This paper presents a shape-based approach to compute, in an optimal sense, the control of a single degree-of-freedom point absorber wave energy converter. In this study, it is assumed that a prediction for the wave is available. The control is computed so as to maximize the energy extraction over a future time horizon. In the shape-base approach, one of the system states is represented by a series expansion. The optimization variables are selected to be the coefficients in the series expansion instead of the history of the control variable. A gradient-based optimizer is used to optimize the series coefficients. The available wave prediction is used to compute an initial guess for the unknown series coefficients. This concept is tested on two different dynamic models: a simplified reduced-order model and a dynamic model with radiation dynamic states necessary to compute the radiation force. Several test cases are presented that cover a range of different sea states. The results show that the shape-based approach finds efficient solutions in terms of the extracted energy. The results also show that the obtained solutions are suitable for real-time implementation in terms of the smoothness of the obtained control and the speed of computations. Comparisons between the results of the shape-based approach and other techniques are presented and discussed.
@article{Abdelkhalik:2016aa, author = {Abdelkhalik, Ossama and Robinett, Rush and Zou, Shangyan and Bacelli, Giorgio and Coe, Ryan and Bull, Diana and Wilson, David and Korde, Umesh}, bibtex_show = true, date-added = {2020-10-07 12:38:58 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1007/s40722-016-0048-4}, file = {Abdelkhalik2016.pdf:pdfs/Abdelkhalik2016.pdf:PDF}, groups = {AdvWecCntrls Pubs}, issn = {2198-6452}, journal = {Journal of Ocean Engineering and Marine Energy}, number = {4}, owner = {rcoe}, pages = {473--483}, publisher = {Springer}, timestamp = {2016.05.02}, title = {On the control design of wave energy converters with wave prediction}, url = {http://dx.doi.org/10.1007/s40722-016-0048-4}, volume = {2}, year = {2016}, bdsk-url-1 = {http://dx.doi.org/10.1007/s40722-016-0048-4} } - Estimation of excitation force on wave energy converters using pressure measurements for feedback controlOssama Abdelkhalik, Shangyan Zou, Giorgio Bacelli, Rush D. Robinett, David G. Wilson, and Ryan G. CoeIn OCEANS 2016 MTS/IEEE Monterey, Sep 2016
Many of the control strategies for wave energy converters (WECs) that have been studied in the literature rely on the availability of estimates for either the wave elevation or the exciting force caused by the incoming wave; with the objective of addressing this issue, this paper presents the design of a state estimator for a WEC. In particular, the work described in this paper is based on an extended Kalman filter that uses measurements from pressure sensors located on the hull of the WEC to estimate the wave exciting force. Simulation results conducted on a heaving point absorber WEC shows that the extended Kalman filter provides a good estimation of the exciting force in the presence of measurement noise combined with a simplified model of the system, thus making it a suitable candidate for the implementation in an experimental set-up.
@inproceedings{Abdelkhalik:2016ab, address = {Monterey, CA, USA}, author = {Abdelkhalik, Ossama and Zou, Shangyan and Bacelli, Giorgio and Robinett, Rush D. and Wilson, David G. and Coe, Ryan G.}, bibtex_show = true, booktitle = {OCEANS 2016 MTS/IEEE Monterey}, date-added = {2020-10-07 12:38:51 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1109/OCEANS.2016.7761227}, file = {Abdelkhalik2016b.pdf:.\\pdfs\\Abdelkhalik2016b.pdf:PDF;Abdelkhalik2016b.pdf:pdfs\\Abdelkhalik2016b.pdf:PDF}, groups = {AdvWecCntrls Pubs}, keywords = {Kalman filters;feedback;measurement errors;nonlinear filters;power generation control;pressure measurement;pressure sensors;wave power generation;WEC;excitation force estimation;exciting force;extended Kalman filter;feedback control;heaving point absorber;measurement noise;pressure measurements;pressure sensors;state estimator;wave elevation;wave energy converters;Computational modeling;Electronic mail;Estimation;Force;Kalman filters;Mathematical model;Sea measurements}, month = sep, pages = {1-6}, publisher = {IEEE}, title = {Estimation of excitation force on wave energy converters using pressure measurements for feedback control}, url = {https://doi.org/10.1109/OCEANS.2016.7761227}, year = {2016}, bdsk-url-1 = {https://doi.org/10.1109/OCEANS.2016.7761227} } - A comparison of WEC control strategies for a linear WEC modelGiorgio Bacelli, Ryan G. Coe, David Wilson, Ossama Abdelkhalik, Umesh A. Korde, Rush D. Robinett III, and Diana L. BullIn Proceedings of the 4th Marine Energy Technology Symposium (METS2016), Apr 2016
In this study, we employ a numerical model to compare the performance of a number of wave energy converter (WEC) control strategies. Each control strategy was evaluated on a single numerical model using sea states to represent a deployment site of the coast of Newport, OR. A number of metrics, ranging from power-flow char- acteristics to kinematics are employed to provide a comparison of each control strategy’s performance.
@inproceedings{Bacelli:2016aa, address = {Washington, D.C.}, author = {Bacelli, Giorgio and Coe, Ryan G. and Wilson, David and Abdelkhalik, Ossama and Korde, Umesh A. and Robinett III, Rush D. and Bull, Diana L.}, bibtex_show = true, booktitle = {Proceedings of the 4th {Marine} {Energy} {Technology} {Symposium} (METS2016)}, date-added = {2020-10-07 12:37:21 -0600}, date-modified = {2025-08-20 18:42:32 -0600}, file = {Bacelli2016.pdf:pdfs/Bacelli2016.pdf:PDF}, groups = {AdvWecCntrls Pubs}, month = apr, owner = {rcoe}, timestamp = {2016.04.30}, title = {A comparison of {WEC} control strategies for a linear {WEC} model}, url = {https://www.osti.gov/servlets/purl/1365131}, year = {2016}, bdsk-url-1 = {https://www.osti.gov/servlets/purl/1365131} } - A comparison of WEC control strategiesDavid Wilson, Giorgio Bacelli, Ryan G. Coe, Diana L. Bull, Ossama Abdelkhalik, Umesh A. Korde, and Rush D. Robinett IIIApr 2016
@techreport{Wilson:2016ab, address = {Albuquerque, NM}, author = {Wilson, David and Bacelli, Giorgio and Coe, Ryan G. and Bull, Diana L. and Abdelkhalik, Ossama and Korde, Umesh A. and Robinett III, Rush D.}, bibtex_show = true, date-added = {2020-10-07 12:36:43 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.2172/1431291}, file = {Wilson2016.pdf:pdfs/Wilson2016.pdf:PDF}, groups = {AdvWecCntrls Pubs}, institution = {Sandia National Labs}, month = apr, number = {SAND2016-4293}, owner = {rcoe}, timestamp = {2016.04.06}, title = {A comparison of {WEC} control strategies}, url = {https://www.osti.gov/biblio/1431291}, year = {2016}, bdsk-url-1 = {https://www.osti.gov/biblio/1431291-comparison-wec-control-strategies}, bdsk-url-2 = {https://doi.org/10.2172/1431291} } - WEC and Support Bridge Control Structural Dynamic Interaction AnalysisDavid Wilson, Giorgio Bacelli, Ryan G. Coe, Rush D. Robinett III, Gareth Thomas, Daniel Linehan, David Newborn, and Miguel QuinteroIn Proceedings of the 4th Marine Energy Technology Symposium (METS2016), Apr 2016
Experimental testing is a critical step in the development of models describing the behavior of a system. The objective of the experimental testing presented in this document is to obtain models for the design of control systems for a Wave Energy Converter (WEC). The particular WEC considered here is a heaving point absorber composed of a floating buoy (see Fig. 1) connected to a support structure through a linear actuator. The support structure is then attached to the side of a bridge (see Fig. 2). The testing will be conducted at the Maneuverability and Seakeeping (MASK) basin located at the Naval Surface Warfare Center Carderock Division (NSWCCD), Bethesda, MD. The actuator applies a force between the floating body and the support structure in order to absorb power from waves. The simplest control strategy that is commonly used for power absorption is linear damping, where the force applied by the actuator is proportional to the velocity of the buoy; in practice, this constitutes a very simple static feedback (no dynamics in the feedback loop): where F u is the actuator’s force, v is the velocity of the buoy and B is the damping coefficient. The support structure cannot be assumed to behave as a fixed reference, thus the actuator connects two oscillating structures (the bridge/support structure and the WEC). Both a modal analysis and experimental testing have been conducted by ATA Engineering on the bridge in order to study the dynamical response of the bridge. Figure 5 depicts the frequency response function (FRF), and it can be seen that the lowest two modes of interest (vertical bending and torsional) are very close to the range of frequencies that will be used for the testing of wave-body interactions by means of waves in the range of 0.4− 1.0 Hz. The objective of this paper is to analyze the potential adverse effects of having a feedback control system applied between these two structures that have close resonance frequencies, and to propose a control design solution for the mitigation of these interactions.
@inproceedings{Wilson:2016aa, address = {Washington, D.C.}, author = {Wilson, David and Bacelli, Giorgio and Coe, Ryan G. and Robinett III, Rush D. and Thomas, Gareth and Linehan, Daniel and Newborn, David and Quintero, Miguel}, bibtex_show = true, booktitle = {Proceedings of the 4th {Marine} {Energy} {Technology} {Symposium} (METS2016)}, date-added = {2020-10-07 12:36:43 -0600}, date-modified = {2025-08-20 18:43:58 -0600}, file = {Wilson2016a.pdf:pdfs/Wilson2016a.pdf:PDF}, groups = {AdvWecCntrls Pubs}, month = apr, owner = {rcoe}, timestamp = {2016.04.30}, title = {{WEC} and Support Bridge Control Structural Dynamic Interaction Analysis}, url = {https://www.osti.gov/servlets/purl/1346307}, year = {2016}, bdsk-url-1 = {https://www.osti.gov/servlets/purl/1346307} } - Advanced WEC Dynamics & Controls FY16 Testing ReportRyan G. Coe, Giorgio Bacelli, David Patterson, and David G. WilsonOct 2016
@techreport{Coe:2016ab, address = {Albuquerque, NM}, author = {Coe, Ryan G. and Bacelli, Giorgio and Patterson, David and Wilson, David G.}, bibtex_show = true, date-added = {2020-10-07 12:35:05 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.2172/1330189}, groups = {AdvWecCntrls Pubs}, institution = {Sandia National Labs}, month = oct, number = {SAND2016-10094}, owner = {rcoe}, timestamp = {2016.10.05}, title = {{A}dvanced {WEC} {D}ynamics \& {C}ontrols {FY16} Testing Report}, url = {https://doi.org/10.2172/1330189}, year = {2016}, bdsk-url-1 = {https://mhkdr.openei.org/submissions/151}, bdsk-url-2 = {https://doi.org/10.2172/1330189} }
2015
- Comparison of methods for estimating short-term extreme response of wave energy convertersCarlos Michelen, and Ryan CoeIn OCEANS 2015 - MTS/IEEE, Oct 2015
Short-term extreme response statistics are often required to obtain the long-term (deployment life) response for an offshore structure. A number of methods are available to produce these response statistics for data collected from either physical experimentation or numerical modeling. Here, we consider the application of a series of such methods to determine the short-term extreme response statistics for a simple wave energy converter (WEC). Using data created from a frequency-domain model, each method is implemented multiple times to provide an understanding of its accuracy and variance. The results are compared along with an empirical "truth" result that uses all of the available data. Trade-offs between the amount of data required by a given method and its accuracy are presented and discussed.
@inproceedings{Michelen:2015aa, address = {Washington, D.C.}, author = {Michelen, Carlos and Coe, Ryan}, bibtex_show = true, booktitle = {OCEANS 2015 - MTS/IEEE}, date-added = {2020-10-07 12:48:39 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.23919/OCEANS.2015.7401878}, keywords = {frequency-domain analysis;probability;wave power generation;frequency-domain model;WEC;short-term extreme response statistics;wave energy converters;short-term extreme response estimation;Wave Energy;WEC;Extreme Value;Short-Term Statistics;Design Load}, month = oct, pages = {1-6}, series = {IEEE}, title = {Comparison of methods for estimating short-term extreme response of wave energy converters}, url = {https://ieeexplore.ieee.org/document/7401878}, year = {2015}, bdsk-url-1 = {https://doi.org/10.23919/OCEANS.2015.7401878}, bdsk-url-2 = {https://ieeexplore.ieee.org/document/7401878} } - Preliminary Wave Energy Converters Extreme Load AnalysisYi-Hsiang Yu, Jennifer Van Rij, Ryan Coe, and Mike LawsonIn Proceedings of the ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering, May 2015V009T09A026
Wave energy converter (WEC) devices are designed to sustain the wave-induced loads that they experience during both operational and survival sea states. The extreme values of these forces are often a key cost driver for WEC designs. These extreme loads must be carefully examined during the device design process, and the development of a specific extreme condition modeling method is essential. In this paper, the key findings and recommendations from the extreme conditions modeling workshop hosted by Sandia National Laboratories and the National Renewable Energy Laboratory are reviewed. Next, a study on the development and application of a modeling approach for predicting WEC extreme design load is described. The approach includes midfidelity Monte-Carlo-type time-domain simulations to determine the sea state in which extreme loads occur. In addition, computational fluid dynamics simulations are employed to examine the nonlinear wave and floating-device-interaction-induced extreme loads. Finally, a discussion on the key areas that need further investigation to improve the extreme condition modeling methodology for WECs is presented.
@inproceedings{Yu:2015aa, address = {St. John's, Newfoundland, Canada}, author = {Yu, Yi-Hsiang and Van Rij, Jennifer and Coe, Ryan and Lawson, Mike}, bibtex_show = true, booktitle = {Proceedings of the ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering}, date-added = {2020-10-07 12:44:05 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1115/OMAE2015-41532}, eprint = {https://asmedigitalcollection.asme.org/OMAE/proceedings-pdf/OMAE2015/56574/V009T09A026/4435126/v009t09a026-omae2015-41532.pdf}, month = may, note = {V009T09A026}, series = {International Conference on Offshore Mechanics and Arctic Engineering}, title = {{Preliminary Wave Energy Converters Extreme Load Analysis}}, url = {https://doi.org/10.1115/OMAE2015-41532}, volume = {9: Ocean Renewable Energy}, year = {2015}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2015-41532} } - Control optimization of wave energy converters using a shape-based approachIn ASME Power & Energy, May 2015
@inproceedings{Abdelkhalik:2015aa, address = {San Diego, CA}, author = {Abdelkhalik, O. and Robinett, R. and Bacelli, G. and Coe, R. and Bull, D. and Wilson, D. and Korde, U.}, bibtex_show = true, booktitle = {ASME Power \& Energy}, date-added = {2020-10-07 12:38:51 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, groups = {AdvWecCntrls Pubs}, owner = {rcoe}, timestamp = {2016.05.03}, title = {Control optimization of wave energy converters using a shape-based approach}, year = {2015} } - Instrumentation of a WEC device for controls testingDavid Patterson, Diana Bull, Giorgio Bacelli, and Ryan CoeIn Proceedings of the 3rd Marine Energy Technology Symposium (METS2015), Apr 2015
A set of tests have been planned to determine the extent to which various control strategies can increase the power produced by resonant wave energy conversion (WEC) devices. This paper describes the instrumentation and sensor suite developed for use in these tests. The instrumentation package was selected to si- multaneously sample all the signals with high resolution at a fre- quency up to 1kHz. The sensor suite for measuring parameters used in real-time control strategies will be recorded at a sam- pling frequency of 100Hz. A set of sensors targeted at validating theoretical and numerical models of the device and will also be sampled at 100Hz. A sensor suite comprised of slam panels and high-impact pressure transducers will measure the slam forces on the device. The slam sensors must be sampled at a higher rate of 1kHz to capture any slam events.
@inproceedings{Patterson:2015aa, address = {Washington DC}, author = {Patterson, David and Bull, Diana and Bacelli, Giorgio and Coe, Ryan}, bibtex_show = true, booktitle = {Proceedings of the 3rd {Marine} {Energy} {Technology} {Symposium} (METS2015)}, date-added = {2020-10-07 12:37:32 -0600}, date-modified = {2025-08-20 18:46:47 -0600}, file = {Patterson2015.pdf:pdfs\\Patterson2015.pdf:PDF}, groups = {AdvWecCntrls Pubs}, month = apr, owner = {dlbull}, timestamp = {2015.04.16}, title = {Instrumentation of a {WEC} device for controls testing}, url = {https://www.osti.gov/servlets/purl/1326573}, year = {2015}, bdsk-url-1 = {https://www.osti.gov/servlets/purl/1326573} } - Design of a Physical Point-Absorbing WEC Model on which Multiple Control Strategies will be Tested at Large Scale in the MASK BasinDiana L. Bull, Ryan G. Coe, Mark Monda, Kevin Dullea, Giorgio Bacelli, and David PattersonIn International Offshore and Polar Engineering Conference (ISOPE2015), Apr 2015
A new multi-year effort has been launched by the Department of Energy to validate the extent to which control strategies can increase the power produced by resonant wave energy conversion (WEC) devices. This paper describes the design of a WEC device to be employed by this program in the development and assessment of WEC control strategies. The operational principle of the device was selected to provide a test-bed for control strategies, in which a specific control strategies effectiveness and the parameters on which its effectiveness depends can be empirically determined. Numerical design studies were employed to determine the device geometry, so as to maximize testing opportunities in the Maneuvering and Seakeeping (MASK) Basin at the Naval Surface Warfare Centers David Taylor Model Basin. Details on the physical model including specific components and model fabrication methodologies are presented. Finally the quantities to be measured and the mechanisms of measurement are listed.
@inproceedings{Bull:2015aa, address = {Kona, HI}, author = {Bull, Diana L. and Coe, Ryan G. and Monda, Mark and Dullea, Kevin and Bacelli, Giorgio and Patterson, David}, bibtex_show = true, booktitle = {International Offshore and Polar Engineering Conference (ISOPE2015)}, date-added = {2020-10-07 12:37:24 -0600}, date-modified = {2025-08-20 18:51:01 -0600}, groups = {AdvWecCntrls Pubs}, organization = {International Society of Offshore and Polar Engineers}, owner = {rcoe}, timestamp = {2015.02.02}, title = {Design of a Physical Point-Absorbing {WEC} Model on which Multiple Control Strategies will be Tested at Large Scale in the {MASK} Basin}, url = {https://www.onepetro.org/conference-paper/ISOPE-I-15-268}, year = {2015}, bdsk-url-1 = {https://www.onepetro.org/conference-paper/ISOPE-I-15-268} } - Sensitivity of a Wave Energy Converter Dynamics Model to Nonlinear Hydrostatic ModelsRyan G. Coe, and Diana L. BullIn Proceedings of the ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering (OMAE2015), Apr 2015
A three dimensional time-domain model, based on Cummins equation, has been developed for an axisymmetric point absorbing wave energy converter (WEC) with an irregular cross section. This model incorporates a number of nonlinearities to accurately account for the dynamics of the device: hydrostatic restoring, motion constraints, saturation of the power-take-off force, and kinematic nonlinearities. Here, an interpolation model of the hydrostatic restoring reaction is developed and compared with a surface integral based method. The effects of these nonlinear hydrostatic models on device dynamics are explored by comparing predictions against those of a linear model. For the studied WEC, the interpolation model offers a large improvement over a linear model and is roughly two orders-of-magnitude less computationally expensive than the surface integral based method.
@inproceedings{Coe:2015aa, address = {St. John's, Newfoundland, Canada}, author = {Coe, Ryan G. and Bull, Diana L.}, bibtex_show = true, booktitle = {Proceedings of the ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering (OMAE2015)}, date-added = {2020-10-07 12:35:05 -0600}, date-modified = {2025-10-02 08:05:37 -0600}, doi = {10.1115/OMAE2015-41993}, file = {Coe2015.pdf:pdfs\\Coe2015.pdf:PDF}, groups = {Nonlinear Cummins Models, AdvWecCntrls Pubs}, organization = {ASME}, owner = {rcoe}, timestamp = {2015.01.07}, title = {Sensitivity of a Wave Energy Converter Dynamics Model to Nonlinear Hydrostatic Models}, url = {https://doi.org/10.1115/OMAE2015-41993}, volume = {9: Ocean Renewable Energy}, year = {2015}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2015-41993} }
2014
- Model validation using experimental measurements from the Garfield Thomas water tunnel at the Applied Research Laboratory (ARL) at Penn State UniversityBudi Gunawan, Carlos Michelen, Vincent S Neary, Ryan G. Coe, Erik Johnson, Arnold Fontaine, Richard S Meyer, William Straka, Michael Jonson, and othersIn Proceedings of the 2nd Marine Energy Technology Symposium (METS2014), Apr 2014
This paper describes the development of a high‐fidelity computational fluid dynamics (CFD) model of a three‐blade horizontal axis current turbine. The CFD model was developed using STAR‐CCM+ and solves the Reynolds‐Averaged Navier‐Stokes (RANS) equation for unsteady flows. Preliminary CFD model results are compared to laboratory measurements. The variables being compared include inflow and wake flow velocity profiles, and performance coefficients (power, thrust and torque coefficients) at different tip‐speed ratios. A preliminary comparison suggests that overall the CFD simulation results have a good agreement with the measurements.
@inproceedings{Gunawan:2014aa, address = {Seattle, WA}, author = {Gunawan, Budi and Michelen, Carlos and Neary, Vincent S and Coe, Ryan G. and Johnson, Erik and Fontaine, Arnold and Meyer, Richard S and Straka, William and Jonson, Michael and others}, bibtex_show = true, booktitle = {Proceedings of the 2nd {Marine} {Energy} {Technology} {Symposium} (METS2014)}, date-added = {2020-10-07 12:54:44 -0600}, date-modified = {2025-08-20 18:52:17 -0600}, month = apr, title = {Model validation using experimental measurements from the {Garfield Thomas} water tunnel at the {Applied Research Laboratory (ARL) at Penn State University}}, url = {http://hdl.handle.net/10919/49214}, year = {2014}, bdsk-url-1 = {http://hdl.handle.net/10919/49214} } - Extreme Conditions Modeling Workshop ReportJul 2014
@techreport{Coe:2014ac, address = {Albuquerque, NM}, author = {Coe, Ryan G. and Neary, Vincent S. and Lawson, Michael J. and Yu, Yi-Hsiang and Weber, Jochem}, bibtex_show = true, date-added = {2020-10-07 12:42:18 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.2172/1149224}, institution = {Sandia National Laboratories}, keywords = {TIDAL AND WAVE POWER; WAVE ENERGY CONVERTER; WEC; EXTREME CONDITIONS MODELING; ECM; Ocean Energy}, month = jul, number = {SAND2014-16384R}, title = {Extreme Conditions Modeling Workshop Report}, url = {https://www.osti.gov/biblio/1149224}, year = {2014}, bdsk-url-1 = {https://www.osti.gov/biblio/1149224}, bdsk-url-2 = {https://doi.org/10.2172/1149224} } - Nonlinear Time-Domain Performance Model for a Wave Energy Converter in Three DimensionsRyan G. Coe, and Diana L. BullIn Proceedings of OCEANS2014, Sep 2014
A nonlinear three-dimensional time-domain performance model has been developed for a floating axisymmetric point absorbing WEC. This model employs a set of linear partial differential equations, in the form of a state-space model, to replace the convolution integrals needed to solve for radiation reaction. Linear time-domain results are verified against predictions from a frequency-domain model. Nonlinear time-domain predictions are compared back to frequency-domain and linear time-domain predictions to show the effects of some linearization assumptions. A simple resistive control strategy is applied throughout these scenarios.
@inproceedings{Coe:2014aa, address = {St. John's, Newfoundland, Canada}, author = {Coe, Ryan G. and Bull, Diana L.}, bibtex_show = true, booktitle = {Proceedings of OCEANS2014}, date-added = {2020-10-07 12:35:05 -0600}, date-modified = {2025-08-20 18:53:32 -0600}, doi = {10.1109/OCEANS.2014.7003037}, file = {Coe2014.pdf:pdfs\\Coe2014.pdf:PDF}, groups = {Nonlinear Cummins Models, AdvWecCntrls Pubs}, month = sep, organization = {IEEE}, owner = {rcoe}, timestamp = {2014.07.31}, title = {Nonlinear Time-Domain Performance Model for a Wave Energy Converter in Three Dimensions}, url = {https://ieeexplore.ieee.org/document/7003037}, year = {2014}, bdsk-url-1 = {https://ieeexplore.ieee.org/document/7003037}, bdsk-url-2 = {https://doi.org/10.1109/OCEANS.2014.7003037} } - Review of Methods for Modeling Wave Energy Converter Survival in Extreme Sea StatesRyan G. Coe, and Vincent S. NearyIn Marine Energy Technology Symposium (METS), Sep 2014
Survivability is by no means a new concept to ocean engineering; ships must remain stable and structurally intact in violent sea states; the same is true for offshore oil and gas structures. While knowledge from the ship and offshore sectors can be valuable for designing wave energy converters (WECs) for survival in rough seas, the unique scale, siting and operational characteristics of WECs pose a distinct set of engineering challenges. This paper seeks to provide a review of methods for modeling the loading and dynamic response of WECs and analogue marine structures, such as ships and offshore structures, in large nonlinear waves. We identify current knowledge gaps in our understanding of WEC survivability and provide recommendations for future research to close these gaps.
@inproceedings{Coe:2014ab, address = {Seattle, WA}, author = {Coe, Ryan G. and Neary, Vincent S.}, bibtex_show = true, booktitle = {Marine Energy Technology Symposium (METS)}, date-added = {2020-10-07 12:35:05 -0600}, date-modified = {2025-08-20 18:55:01 -0600}, file = {:pdfs\\CoeNeary2014.pdf:PDF}, owner = {rcoe}, timestamp = {2015.02.02}, title = {Review of Methods for Modeling Wave Energy Converter Survival in Extreme Sea States}, url = {http://hdl.handle.net/10919/49221}, year = {2014}, bdsk-url-1 = {http://hdl.handle.net/10919/49221} }
2013
- CFD-Based Maneuvering Simulations for Autonomous Underwater VehiclesRyan G. Coe, Brian R. McCarter, and Wayne L. NeuIn Virginia Space Grant Consortium Student Research Conference, Sep 2013
@inproceedings{Coe:2013aa, address = {Norfolk, VA}, author = {Coe, Ryan G. and McCarter, Brian R. and Neu, Wayne L.}, bibtex_show = true, booktitle = {Virginia Space Grant Consortium Student Research Conference}, date-added = {2020-10-07 15:14:40 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, title = {{CFD}-Based Maneuvering Simulations for Autonomous Underwater Vehicles}, url = {http://www.vsgc.odu.edu/awardees/20122013/abstracts/Papers - Grad/Coe, Ryan - Paper.pdf}, year = {2013}, bdsk-url-1 = {http://www.vsgc.odu.edu/awardees/20122013/abstracts/Papers%20-%20Grad/Coe,%20Ryan%20-%20Paper.pdf} } - Use of Overset Mesh to Allow Dynamic Deflection of Tight-Fitting Control Surfaces in CFD SimulationsRyan G. Coe, and Wayne L. NeuIn Proceedings of the ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering, Jun 2013V007T08A051
The development of vehicle maneuvering simulations based within computational fluid dynamics (CFD) environments demands that vehicle control surfaces be dynamically deflected during such simulations. This paper details the process of developing and testing CFD simulation methods that allow for the deflection of a specific AUV’s control surfaces. This task is made particularly challenging by the geometry of the AUV, as its moving control surfaces fit very closely to stationary fixed strakes and the AUV’s hull (a fairly common trait among this class of vehicles). After ruling out embedded and deformable mesh approaches, an overset mesh method is applied. Steady-state simulations with this overset mesh show general agreement with static mesh simulations. The two approaches do, however, highlight the mesh sensitivity of CFD simulations in their ability to predict the onset of stall.
@inproceedings{Coe:2013ac, address = {Nantes, France}, author = {Coe, Ryan G. and Neu, Wayne L.}, bibtex_show = true, booktitle = {Proceedings of the ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering}, date-added = {2020-10-07 15:14:11 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1115/OMAE2013-10931}, eprint = {https://asmedigitalcollection.asme.org/OMAE/proceedings-pdf/OMAE2013/55416/V007T08A051/4431565/v007t08a051-omae2013-10931.pdf}, month = jun, note = {V007T08A051}, series = {International Conference on Offshore Mechanics and Arctic Engineering}, title = {{Use of Overset Mesh to Allow Dynamic Deflection of Tight-Fitting Control Surfaces in CFD Simulations}}, url = {https://doi.org/10.1115/OMAE2013-10931}, volume = {7: CFD and VIV}, year = {2013}, bdsk-url-1 = {https://doi.org/10.1115/OMAE2013-10931} } - Improved underwater vehicle control and maneuvering analysis with computational fluid dynamics simulationsRyan Geoffrey CoeVirginia Tech, Jun 2013
The quasi-steady state-space models generally used to simulate the dynamics of underwater vehicles perform well in most steady flow scenarios, and are therefore acceptable for modeling today’s fleet of endurance-focused autonomous underwater vehicles (AUVs). However, with their usage of numerous assumptions and simplifications, these models are not well suited to certain unsteady flow situations and for use in the development of AUVs capable of performing more extreme maneuvers. In the interest of better serving efforts to design a new generation of more maneuverable AUVs, a tool for simulating vehicle maneuvering within computational fluid dynamics (CFD) based environments has been developed. Unsteady Reynolds-averaged Navier-Stokes (URANS) simulations are used in conjunction with a 6-degree-of-freedom (6-DoF) rigid-body kinematic model to provide a numerical test basin for vehicle maneuvering simulations. The accuracy of this approach is characterized through comparison with experimental measurements and quasi-steady state-space models. Three state-space models are considered: one model obtained from semi-empirical database regression (this is the method most commonly used in application) and two models populated with coefficients determined from the results of prescribed motion CFD simulations. CFD analyses focused on supporting the design of a general purpose AUV are also presented.
@phdthesis{Coe:2013ab, address = {Blacksburg, VA}, author = {Coe, Ryan Geoffrey}, bibtex_show = true, date-added = {2020-10-07 12:50:49 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, school = {Virginia Tech}, title = {Improved underwater vehicle control and maneuvering analysis with computational fluid dynamics simulations}, url = {http://hdl.handle.net/10919/23777}, year = {2013}, bdsk-url-1 = {http://hdl.handle.net/10919/23777} }
2012
- Design and testing of a Self-Mooring AUVBrian R. McCarter, Robert Briggs, Sean Portner, Dan Stilwell, Wayne Neu, Ryan Coe, Richard Duelley, Dexter Malley, and Jason MimsIn 2012 OCEANS, Oct 2012
The Virginia Tech Self-Mooring AUV is capable of mooring itself on the seafloor. Its principal mission is to deploy bottom-mounted sensors without the need for a support ship to visit the mooring location. The mooring concept was previously demonstrated using a small-scale prototype. It has, more recently, been transitioned to a full-scale system and successfully demonstrated in the field. In this paper, we document the design of the full-scale vehicle and present results from field trials.
@inproceedings{McCarter:2012aa, address = {Hampton Roads, VA, USA}, author = {McCarter, Brian R. and Briggs, Robert and Portner, Sean and Stilwell, Dan and Neu, Wayne and Coe, Ryan and Duelley, Richard and Malley, Dexter and Mims, Jason}, bibtex_show = true, booktitle = {2012 OCEANS}, date-added = {2020-10-07 12:59:50 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1109/OCEANS.2012.6405053}, issn = {0197-7385}, keywords = {autonomous underwater vehicles;oceanographic equipment;sensors;Virginia Tech self-mooring AUV;seafloor;bottom-mounted sensors;mooring location;full-scale vehicle;Vehicles;Propellers;Nose;Sensors;Drag;Electron tubes}, month = oct, pages = {1-8}, title = {Design and testing of a Self-Mooring {AUV}}, url = {https://doi.org/10.1109/OCEANS.2012.6405053}, year = {2012}, bdsk-url-1 = {https://doi.org/10.1109/OCEANS.2012.6405053} } - Virtual planar motion mechanism tests in a CFD environmentRyan Coe, and Wayne NeuIn Virginia Space Grant Consortium Student Research Conference, Oct 2012
A study is currently underway to better understand and influence the maneuvering characteristics of autonomous underwater vehicles (AUVs). A two-pronged approach, using traditional quasi-steady state-space modeling as well as maneuvering experiments performed in unsteady Reynolds-averaged Navier-Stokes simulations (URANS), has been adopted to provide the greatest possible insight into vehicle modeling. State-space models must be populated with parameters describing the vehicle of interest. This paper focuses on the use of a virtual planar motion mechanism (PMM) method to find hydrodynamic maneuvering characteristics within a computational fluid dynamics (CFD) environment.
@inproceedings{Coe:2012aa, author = {Coe, Ryan and Neu, Wayne}, bibtex_show = true, booktitle = {Virginia Space Grant Consortium Student Research Conference}, date-added = {2020-10-07 12:59:38 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, title = {Virtual planar motion mechanism tests in a {CFD} environment}, url = {https://www.academia.edu/18038713/VIRTUAL_PLANAR_MOTION_MECHANISM_TESTS_IN_A_CFD_ENVIRONMENT}, year = {2012}, bdsk-url-1 = {https://www.academia.edu/18038713/VIRTUAL_PLANAR_MOTION_MECHANISM_TESTS_IN_A_CFD_ENVIRONMENT} } - Asymmetrical wake and propulsor effects on control surface effectiveness on AUVsRyan G. Coe, and Wayne L. NeuIn 2012 Oceans, Oct 2012
This study considers the influences of wake asymmetries and propulsor effects on the forces and moments created by control surfaces. Traditional quasi-steady state-space models developed for autonomous underwater vehicles (AUVs) tend to neglect these effects. Reynolds-averaged Navier-Stokes (RANS) simulations were used to assess the impact of asymmetrical inflow due to forward appendages as well as changes in the flow field created by an operating propeller on control surface effectiveness. For the AUV tested, substantial asymmetries in the flow field near the upper and lower rudders create significant differences in their respective performances. This discrepancy between the rudders has the potential to create considerable and unsuspected maneuvering reactions. The presence of the propeller was also seen to noticeably influence the performance of the control surfaces.
@inproceedings{Coe:2012ab, address = {Hampton Roads, VA, USA}, author = {Coe, Ryan G. and Neu, Wayne L.}, bibtex_show = true, booktitle = {2012 Oceans}, date-added = {2020-10-07 12:53:07 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1109/OCEANS.2012.6404941}, issn = {0197-7385}, keywords = {autonomous underwater vehicles;flow;hydrodynamics;motion control;Navier-Stokes equations;propellers;vehicle dynamics;wakes;asymmetrical wake effects;propulsor effects;control surface effectiveness;AUV;autonomous underwater vehicles;quasi-steady state-space models;Reynolds-averaged Navier-Stokes simulations;RANS;asymmetrical inflow impact assessment;upper rudders;lower rudders;unsuspected maneuvering reactions;quasi-steady state-space hydrodynamic models;Propellers;Sea surface;Vehicles;Computational modeling;Actuators;Underwater vehicles;Surface treatment}, month = oct, pages = {1-4}, title = {Asymmetrical wake and propulsor effects on control surface effectiveness on {AUVs}}, url = {https://doi.org/10.1109/OCEANS.2012.6404941}, year = {2012}, bdsk-url-1 = {https://doi.org/10.1109/OCEANS.2012.6404941} } - Amplitude effects on virtual PMM testsRyan G. Coe, and Wayne L. NeuIn 2012 Oceans, Oct 2012
Planar Motion Mechanism (PMM) testing provides a means of determining the performance characteristics (often referred to as control derivatives or maneuvering coefficients) that populate vehicle quasi-steady state-space models. While the general nature of these tests is fairly well established, the details of execution and post processing methods vary between experimenters. This study employs numerical simulations to examine the use of a number of common force decomposition models across a range of amplitudes of oscillation. The results show that the force decomposition models examined perform similarly well at low amplitude, however accuracy appears to decline at higher amplitudes of motion with the increasing prevalence of unmodeled viscous flow phenomena.
@inproceedings{Coe:2012ac, address = {Hampton Roads, VA, USA}, author = {Coe, Ryan G. and Neu, Wayne L.}, bibtex_show = true, booktitle = {2012 Oceans}, date-added = {2020-10-07 12:52:07 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, doi = {10.1109/OCEANS.2012.6405027}, issn = {0197-7385}, keywords = {computational fluid dynamics;flow;marine vehicles;motion control;numerical analysis;state-space methods;amplitude effects;virtual PMM tests;planar motion mechanism testing;control derivatives;maneuvering coefficients;quasi-steady state-space models;numerical simulations;force decomposition models;oscillation amplitudes;motion amplitudes;unmodeled viscous flow phenomena;marine vehicle control design;computational fluid dynamics;Force;Oscillators;Vehicles;Numerical models;Hydrodynamics;Testing;Damping}, month = oct, pages = {1-5}, title = {Amplitude effects on virtual {PMM} tests}, url = {https://doi.org/10.1109/OCEANS.2012.6405027}, year = {2012}, bdsk-url-1 = {https://doi.org/10.1109/OCEANS.2012.6405027} }
2011
- Vehicle Control in a CFD EnvironmentRyan G. Coe, and Wayne L. NeuIn Grand Challenges on Modeling and Simulation Conference, Oct 2011
Work in progress toward a tool for synchronous control algorithm design and vehicle hydrodynamic analysis via CFD is discussed. A commercial CFD code, with minor augmentations, will serve as a high-fidelity hydrodynamic model to be run in parallel with and loosely coupled to a candidate control algorithm allowing the vehicle to be computationally flown under the influence of that control. A number of components of this tool have been developed and are described. These include a momentum based propeller model which simulates both added axial and swirl velocities and a control surface force parameterization which will be used as a first approximation while a mesh morphing scheme for deflecting control surfaces is implemented. The accuracy of the CFD approach is demonstrated by comparison with experimental data for drag on a DARPA SUBOFF model and for skin friction and flow separation on a prolate spheroid at an angle of attack. Unsteady nonlinear effects are demonstrated with a simulation of a spheroid propagating through water in the presence of an oscillating sway force. The direction of future work is also presented.
@inproceedings{Coe:2011aa, address = {The Hague, Netherlands}, author = {Coe, Ryan G. and Neu, Wayne L.}, bibtex_show = true, booktitle = {Grand Challenges on Modeling and Simulation Conference}, date-added = {2020-10-07 15:17:57 -0600}, date-modified = {2025-06-25 12:01:07 -0600}, title = {Vehicle Control in a {CFD} Environment}, url = {http://dl.acm.org/citation.cfm?id=2348229.2348281}, year = {2011}, bdsk-url-1 = {http://dl.acm.org/citation.cfm?id=2348229.2348281} }