Fault-Tolerant Control for Unmanned Marine Vehicles via Quantized Integral Sliding Mode Output Feedback Technique

This paper presents a fault-tolerant control method based on the integral sliding mode (ISM) output feedback technique for the dynamic positioning control of an unmanned marine vehicle (UMV) subject to signal quantization and thruster faults. By using output information and estimates of thruster effectiveness factors, a novel integral sliding manifold is first constructed to maintain that the sliding function of system output equals the one of quantized output, which removes the region restriction that exists in the literature. Then based on the quantized signals of system output, a compensator is designed to introduce some degrees of design flexibility. To conquer the quantization effects, we incorporate a dynamic quantization parameter adjustment strategy and the fault-tolerant technique into the ISM output feedback control algorithm. The relation between the attraction area and quantization range has been revealed for the first time. Finally, the closed-loop stability can be guaranteed from every beginning time in despite of the quantization and thruster faults. Simulation through a typical floating production ship has verified the effectiveness of the proposed method.