Path Tracking Control for the Docking of Unmanned Surface Vessel

Avoiding collision between the unmanned surface vessel (USV) and the compartment of the mother ship is an important issue during the process of autonomous docking of the USV. To address this challenge, a new path-tracking control strategy utilized for the USV docking is proposed in this paper. Firstly, a geometric constraint model based on the lateral and yaw angle tracking errors is established for the docking scenario, and both the path curvature and the distance from the USV to the docking compartment are introduced to the design of the surge velocity. Then, the unmeasurable velocities and the lumped disturbances are estimated by using an extended state observer, and an adaptive super-twisting sliding mode controller is designed to improve the path-tracking accuracy and anti-disturbance ability. Finally, the effectiveness and the robustness of the controller are verified through numerical simulation.