Wave Excitation Force Estimation for Wave Energy Converters Using Square Root Unscented Kalman Filters

In wave energy converters (WECs), operative control strategies require the wave excitation force to be known and available in real time. Unfortunately, the force is immeasurable and can only be estimated from other measurable quantities. This paper proposes a square root unscented Kalman filter (SR-UKF) to estimate the wave excitation force acting on a heaving WEC. The estimator depends on available measurements of the WEC mechanical states and has the ability to incorporate WEC nonlinearities. The SR-UKF estimation performance is tested under several sea state scenarios and verified through MATLAB simulation. The SR-UKF exhibits satisfactory estimation accuracy, with a goodness of fit between 98.5% - 93.4% for all investigated scenarios.