Sliding mode fault-tolerant control for unmanned marine vehicles with signal quantization and time-delay

This paper deals with the adaptive sliding mode fault-tolerant control problem for unmanned marine vehicles (UMVs) with signal quantization and state time-delay. A unified thruster fault model for UMVs is built by taking bias, partial, total, time-varying stuck, and hard-over faults into account. For UMVs in the network environment, the effects of quantization and state time-delay on UMVs are inevitable. In this situation, adaptive sliding mode technology and dynamic quantization parameter adjustment strategy are combined to compensate for the quantization errors and time-delay effects. Compared with the traditional method, a larger quantization parameter adjustment range is given and a new dynamic quantization parameter adjustment strategy is designed. Further the quantized sliding mode fault-tolerant controller independent of fault detection and diagnosis mechanism is designed for UMVs in the presence of time-delay and various thruster faults to reduce the oscillation amplitudes of the yaw velocity error. The comparison simulations of a typical floating production ship have been provided to demonstrate the effectiveness of the proposed algorithm.