A class of globally stabilising controllers for the control of wave energy devices for potable water production

This paper provides a stability analysis for a system that captures wave energy in order to produce potable water. The system, introduced in [1], is a Wave Energy Converter (WEC) of the point-absorber type coupled to a hydraulic Power Take-Off (PTO) that converts wave energy into pressure. Previous work has used a partial state-feedback controller with integral action and feed-forward to provide good nominal control behaviour. Although open-loop stability was proven in [1], no guarantees of closed-loop stability were given; in this paper we provide such guarantees for a class of controllers, of which the controller proposed in [1] is a special case.