Sliding mode H-infinity control for offshore steel jacket platforms subject to nonlinear self-excited wave force and external disturbance

This paper is concerned with sliding mode H∞ control for an offshore steel jacket platform subject to nonlinear self-excited wave force and external disturbance. A sliding mode H∞ controller is designed to reduce the oscillation amplitudes of the offshore platform. In the case that the dynamic model of the offshore platform is subject to parameter perturbations, a robust sliding mode H∞ control scheme is proposed. It is found through simulation results that (i) compared with an H∞ controller and a sliding mode controller, the sliding mode H∞ controller requires much less control force, and (ii) the oscillation amplitudes of the offshore platform under the sliding mode H∞ controller are less than those under the sliding mode controller.