Robust adaptive control of dynamic positioning ship under thruster faults and unknown disturbances

The robust adaptive anti-disturbance fault-tolerant control strategy for the dynamic positioning (DP) system of ships is built on the disturbance observer, the adaptive fault observer with the vectorial backstepping approach. The disturbance observer is constructed to estimate the first-order Markov disturbances. The adaptive fault observer with the projection algorithm is designed to estimate partial thruster faults. By employing the vectorial backstepping method, the robust adaptive anti-disturbance fault-tolerant control law is developed to simultaneously achieve the disturbance compensation and the partial thruster fault tolerant. It is demonstrated using the Lyapunov functions that the robust adaptive anti-disturbance fault-tolerant controller can maintain the DP of the ship's position and heading to achieve the desired value, while guaranteeing the global stability of all signals in the DP closed-loop control system. Finally, different cases in the unknown ocean disturbance environment demonstrate the effectiveness of the robust adaptive anti-disturbance fault-tolerant control strategy.