Adaptive fault tolerant control of unmanned underwater glider with predefined-time stability

Actuator faults of the underwater gliders (UGs) not only jeopardize the motion control performance but may also threaten the sailing safety. This paper proposes an adaptive sliding mode fault-tolerant controller with predefined-time stability for the UGs, considering the modeling uncertainties and the unknown disturbances. Three types of actuator faults are developed and incorporated in the fault model of the UGs, which are utilized for the fault tolerant controller design. Then, the adaptive terms are utilized to estimate the modeling uncertainties and the unknown disturbances. An adaptive sliding mode fault tolerant controller is thus designed with the theoretical proof that the global stability can be achieved within a predefined time. The hardware-in-the-loop simulations are conducted to verify the effectiveness of the proposed fault tolerant controller. The simulation results show that the UG can achieve the stability of the pitching attitude under three kinds of actuator fault conditions.