Abstract-Advanced control strategies play a crucial role in increasing the energy extraction capacity of wave energy converters (WECs). So far, the most promising control schemes have predominantly been studied in simulation, based on the idealized assumption of the wave excitation force availability in real time. In practical WEC implementations, this is not the case, since this force cannot be measured directly when the WECs are running. Hence the force has to be estimated via measurements of other quantities. Two approaches are presented in this paper to fulfill this objective. The first approach is based on a Kalman filter coupled with a random-walk model of the wave excitation force, while a receding horizon -unknown input estimation approach is employed for the second one. The proposed estimation methods are evaluated by using real measurements from a laboratory scale WEC.
International audienceThe aim of this paper is twofold. In the first part, robust invariance for ellipsoidal sets with respect to uncertain and/or time-varying linear discrete-time systems with bounded additive disturbances is revisited. We provide an extension of an existing invariance condition. In the second part a novelrobust interpolation based control design involving several local unconstrained robust optimal controls is proposed. At each timeinstant a quadratic programming problem is solved on-line. Proofs of recursive feasibility and input-to-state stability are given
This paper addresses the problem of regulating a discrete-time linear uncertain and time-varying system to the origin. It is shown that, based on an interpolation technique, by minimizing an appropriate objective function, how feasibility and a robustly and asymptotically stable closed-loop behavior can be achieved. It is shown that the control is a piecewise affine and continuous function of the state. Several simulations demonstrate the performance of our results.
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