Delayed Robust Non-fragile H∞ Control
This chapter is concerned with a delayed non-fragile H∞ control scheme for an offshore steel jacket platform subject to self-excited nonlinear hydrodynamic force and external disturbance. By intentionally introducing a time-delay into the control channel, a delayed robust non-fragile H∞ controller is designed to reduce the vibration amplitudes of the offshore platform. The positive effects of time-delays on the non-fragile H∞ control for the offshore platform are investigated. It is shown through simulation results that (i) the proposed delayed non-fragile H∞ controller is effective to attenuate vibration of the offshore platform, (ii) the control force required by the delayed non-fragile H∞ controller is smaller than the one by the delay-free non-fragile H∞ controller, and (iii) the time-delays can be used to improve the control performance of the offshore platform.