@article{Forbush_Bacelli_Spencer_Coe_Wilson_Robertson_2022, title={A Self-Tuning WEC Controller for Changing Sea States}, volume={5}, url={https://marineenergyjournal.org/imej/article/view/70}, DOI={10.36688/imej.5.327-338}, abstractNote={<p>A self-tuning proportional-integral control law prescribing<br>motor torques was tested in experiment on a three<br>degree-of-freedom wave energy converter. The control objective<br>was to maximize electrical power. The control law relied upon<br>an identified model of device intrinsic impedance to generate a<br>frequency-domain estimate of the wave-induced excitation force<br>and measurements of device velocities. The control law was tested<br>in irregular sea-states that evolved over hours (a rapid, but<br>realistic time-scale) and that changed instantly (an unrealistic<br>scenario to evaluate controller response). For both cases, the<br>controller converges to gains that closely approximate the postcalculated<br>optimal gains for all degrees of freedom in a sufficiently<br>short-time for realistic sea states. In addition, electrical<br>power was found to be relatively insensitive to gain tuning over<br>a broad range of gains, implying that an imperfectly tuned<br>controller does not result in a large penalty to electrical power<br>capture. Because the controller relies on an identified model of<br>device intrinsic impedance, the sensitivity of power capture was<br>evaluated with respect to uncertainty in the constituent terms<br>of intrinsic impedance. Power capture is found to be relatively<br>insensitive to uncertainty of 20% in constituent terms of the<br>identified intrinsic impedance model. An extension of this control<br>law that allows for adaptation to a changing device impedance<br>model over time is proposed for long-term deployments, as<br>well as an approach to explicitly handle constraints within this<br>architecture.</p>}, number={3}, journal={International Marine Energy Journal}, author={Forbush, Dominic Dean and Bacelli, Giorgio and Spencer, Steven J. and Coe, Ryan G. and Wilson, David G. and Robertson, Bryson}, year={2022}, month={Dec.}, pages={327–338} }