Sliding mode based fault tolerant control for autonomous underwater vehicle

An investigation is conducted into thruster fault tolerant control for autonomous underwater vehicle (AUV) in this paper. In order to reduce the steady error caused by thruster faults in the use of a traditional sliding mode controller, a fault tolerant control method integrated with thrust allocation is proposed based on the sliding mode theory. According to the proposed method, a thruster weighted matrix is introduced, whose value varies depending on the fault magnitude of the thruster. Then, the proposed controller is applied to compensate for the insufficient thrust of the fault thruster. In order to mitigate the chattering phenomenon in the sliding process, the adaptive law that applies to switching gain and the thickness of boundary layer is developed for the proposed controller. The stability of the system is demonstrated by the frame of Lyapunov theory. Finally, a series of pool-experiments on AUV prototype are conducted to validate the proposed method.