Pure delayed non-fragile control for offshore steel jacket platforms subject to non-linear self-excited wave force

This paper is concerned with pure delayed non-fragile control for an offshore steel jacket platform subject to non-linear self-excited wave force. By purposefully introducing a proper time-delay into control channel, a pure delayed non-fragile controller (DNFC) is proposed to improve performance of the offshore steel jacket platform. The positive effects of time-delays on non-fragile stabilization control for the system are investigated. It is shown through simulation results that (i) the DNFC and the delay-free non-fragile controller are capable of attenuating the vibration of the offshore platform to almost the same level, while the required control force under the DNFC is less than that under the delay-free one; and (ii) both the oscillation amplitudes of the offshore platform and the ranges of the control force under the pure delayed state feedback controller (DSFC) are smaller than the ones under the non-linear controller and the dynamic output feedback controller; and (iii) the oscillation amplitudes of the offshore platform under the DSFC are almost the same as the ones under integral sliding mode controller and the delayed dynamic output feedback controller, while the control force required by the former is less than the one by the latter.