Extended State Observer-Based Fixed-time Nonsingular Sliding Mode Trajectory Tracking Control of USVs Subject to Actuator Faults

Aiming at the trajectory tracking control problem of unmanned surface vessels (USVs) with model uncertainty, external disturbances, and actuator faults, a novel fixed-time nonsingular sliding mode control (FxTNSMC) method is proposed based on a fixed-time extended state observer (FxTESO). Firstly, the FxTESO is used to estimate the unmeasured velocities and lumped disturbances of the system, and a prescribed performance function is used to constrain the output errors. Then, combining with a nonsingular fixed-time sliding mode surface, a fixed-time fault-tolerant controller is designed by using the outputs of the observer and the error transformation based on the prescribed performance control (PPC). In addition, according to the Lyapunov stability theorem, the proposed control method enables the tracking errors to quickly converge to zero in a fixed time. Finally, the effectiveness of the proposed method is verified by numerical simulation, and the system has the advantages of strong robustness and high steady-state accuracy.