Sliding mode control for trajectory tracking of autonomous underwater vehicles via predefined time disturbance observer

This paper investigates the trajectory tracking control problem with prescribed performance for autonomous underwater vehicles (AUVs) subject to lumped disturbances composed of model uncertainties and unknown time-varying external disturbances. A practical predefined-time Lyapunov criterion is first established to characterize the closed-loop convergence property. Then, a continuous predefined-time disturbance observer is developed to estimate lumped disturbance within a predefined time. Based on the observer and a nonsingular sliding-mode surface, a prescribed performance sliding mode controller is proposed to ensure that the tracking errors remain within prescribed performance bounds and converge to a preassigned neighborhood within a predefined time, independent of the initial conditions. Finally, simulation results validate the effectiveness of the proposed methodology.