Integrated design of fault diagnosis and adaptive fault-tolerant robust control for submarine's vertical movement

An integrated design of fault diagnosis and adaptive fault-tolerant robust control for a submarine with bow and stern rudder faults is proposed in this paper. Considering the disturbance coming from waves when a submarine operates near sea surface, a simplified linear system with both wave disturbance and the bow and stern rudder faults for submarine's vertical movement is presented. An unknown input observer is designed to decouple wave disturbance and the bow and stern rudder faults. Then an adaptive law is designed to estimate rudder fault parameters without any prior fault information. Based on the estimated fault parameters, an adaptive robust fault-tolerant controller is implemented. Simulation results show that the proposed controller has a satisfactory effect in both pitch and depth control when the bow and stern rudders suffer from unknown faults.