Fast and Accurate Trajectory Tracking Control for Underactuated AUVs With Mismatched Disturbances: Theory and Experiment

Abstract

This article focuses on the design of fast and accurate trajectory tracking controller for underactuated autonomous underwater vehicles (AUVs) with mismatched disturbances. First, through model reconstruction, a novel four-degree-of-freedom fully actuated dynamic equation with mismatched disturbances is derived from the six-degree-of-freedom underactuated dynamic equation. Then, a finite-time disturbance observer is utilized to estimate the mismatched disturbances. Next, a nonsingular integral terminal sliding mode control (NITSMC) scheme based on the disturbances estimation is proposed to achieve finite-time trajectory tracking of AUVs. The designed control scheme prevents differential explosions of the control law, suppresses the chattering effect of sliding mode and offers faster convergent speed and higher control accuracy in comparison with the existing adaptive NITSMC (ANITSMC) approach. Finally, the high-fidelity simulations with actual water tank disturbance data and the water tank experiments demonstrate the effectiveness and superiority of the proposed control scheme in contrast to the ANITSMC approach.