  In this paper, we propose a novel approach for controlling surface water
waves and their interaction with floating bodies. We consider a floating target
rigid body surrounded by a control region where we design three control
strategies of increasing complexity: an active strategy based on controlling
the pressure at the air-water interface and two passive strategies where an
additional controlled floating device is designed. We model such device both as
a membrane and as a thin plate and study the effect of this modelling choice on
the performance of the overall controlled system. We frame this problem as an
optimal control problem where the underlying state dynamics is represented by a
system of coupled partial differential equations describing the interaction
between the surface water waves and the floating target body in the frequency
domain. An additional intermediate coupling is then added when considering the
control floating device. The optimal control problem then aims at minimizing a
cost functional which weights the unwanted motions of the floating body. A
system of first-order necessary optimality conditions is derived and
numerically solved using the finite element method. Numerical simulations then
show the efficacy of this method in reducing hydrodynamic loads on floating
objects.
