Robust anti-disturbance fault-tolerant control of ship-board platforms with multiplicative actuator faults and unknown disturbances

Ship-board platform installed on ships as a heave compensation device can compensate for roll, pitch and heave motions of ships, ensuring the safe operations of special tasks such as sea launch, offshore installation and drilling configurations. Due to the harshness of the marine environment, the actuator fails may cause significant economic losses and even casualties. In this paper, the robust anti-disturbance fault-tolerant control scheme for the ship-board platform is built on the disturbance observer, the adaptive fault observer with the vectorial backstepping technique. The external disturbance compensation and actuator fault tolerance are realized separately. Specially, a robustifying term with the adaptive law is inserted to address the unmodeled dynamics of nonlinear systems. It is demonstrated with the Lyapunov functions that the robust adaptive anti disturbance fault-tolerant controller can maintain the ship-board platform's position and orientation to achieve the desired values and guarantee the global stability of the closed-loop ship-board platform control system. Finally, simulation results demonstrate that the compensation of external disturbances and actuator faults can reach 99.1% under 4 sea state, and the compensation performance is increased by 5.7% compared with the existing robust disturbance rejection control, such that the reliability and safety of the system can be improved effectively.