Abstract
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.