Fault Diagnosis and Reconfigurable Control of Autonomous Underwater Vehicles With Actuator Faults and Predefined-Time Stability

Actuator faults threaten the sailing safety of autonomous underwater vehicles (AUVs). This paper proposes a reconfigurable control strategy with fault diagnosis (FD) for AUVs, considering the actuator faults, fault estimation errors, external disturbances, and convergence rate. A FD method is designed to detect and identify the actuator faults accurately in the presence of external disturbance. Then, a reconfiguration mechanism is given to improve the total performance of the switching process. Subsequently, upon identifying fault information and achieving a certain level of reconfiguration accuracy, a sliding mode fault-tolerant control (FTC) with predefined-time stability is employed. This scheme addresses external disturbances and estimation errors collectively by assuming a reasonable constant upper bound. Theoretical proofs are provided to ensure that the designed FTC achieves convergence to desired states within predefined timeframes. Simulation studies under various conditions validate the effectiveness of the proposed reconfiguration strategy.