Design of active backstepping control of actuator faults and prescribed performances.

This study designs a fault-tolerant control (FTC) system for unmanned underwater vehicles (UUVs) with actuator faults, estimation errors, disturbances, prescribed boundaries, and input saturations. The developed FTC system can estimate the total fault effects in UUVs using a robust and simplified fault observer, which considers an auxiliary state variable and a linear matrix inequality. After completing the fault estimation to a certain extent, a robust active FTC method is proposed and developed using a barrier Lyapunov function and auxiliary systems combined with adaptive laws and a backstepping design. The proposed controller achieves stable trajectory tracking with the system's prescribed performance and input saturation. Finally, the feasibility and effectiveness of the proposed observer and controller are illustrated through three simulations.