Sliding mode 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.