A Robust Observer-Based Fault Tolerant Control Scheme for Underwater Vehicles

This paper proposes an actuator failure tolerant robust control scheme for underwater vehicles. A state observer is introduced first, aimed at estimating velocities. In order to solve the tracking problem for vehicle positions, a sliding mode control (SMC) law is developed using the available position measurements and the velocity estimates provided by the observer. Detection of thruster faults based on the check of any deviation of the observed sliding surfaces, and an isolation policy for the failed thruster are proposed. Finally, control reconfiguration is performed exploiting the inherent redundancy of actuators. An extensive simulation study has been performed, supporting the effectiveness of the proposed approach.