Quantized Sliding Mode Control of Unmanned Marine Vehicles: Various Thruster Faults Tolerated With a Unified Model

This paper investigates quantized sliding mode control of unmanned marine vehicles (UMVs) with thruster faults and nonlinearities. We give a unified model to accommodate different types of thruster faults (e.g., partial, total, time-varying stuck, hard-over, and bias faults) in a common framework, which is significant because existing methods can only address them separately in a fault-specific manner. To eliminate the quantization effect induced by the communication channel by which the UMV outputs (e.g., position and velocity) and the control inputs are transmitted to and from the remote control station, a new dynamic uniform quantizer with an adjustable range of sensitivity is given. Via flexible choice of parameters, the adjustment range can fall within that of the existing results in the fault-free case. A quantized sliding mode controller and a dynamic quantization parameter adjustment strategy are then developed to suppress oscillation amplitudes of the yaw velocity error and the yaw angle in the presence of thruster faults. Simulation studies have verified the effectiveness of the proposed method.