Wave excitation force estimation for wave energy converters using adaptive sliding mode observer

A novel adaptive sliding mode observer (ASMO) is proposed to achieve the real-time excitation force estimation for wave energy converters in this paper. The main advantages of the proposed observer include robustness, fast convergence speed and high estimation accuracy. The proposed ASMO is proven to be finite-time convergent with a known convergence time limit, which allows one to estimate in advance when the proposed observer starts to provide accurate information. The robustness of the proposed ASMO is guaranteed by the sliding mode structure and the adaptive method. The coefficients of the proposed observer are time-varying according to the system states and a sliding mode variable is introduced to keep the estimated dynamics close to the actual dynamics. Simulation results show the effectiveness and superiority of the proposed ASMO by comparison with the Kalman Filter.