Autonomous Berthing of Unmanned Surface Vehicles Based on Improved Dubins-RRT Algorithm and Non-Singular Terminal Sliding Mode Control

Autonomous berthing is the last step to achieving the autonomous operation of unmanned surface vehicles (USVs). Due to the significant disturbance of wind, waves, and currents and the uncertainties of the model, it is difficult to realize autonomous berthing. For the case of obstacles and dynamics of USVs, it is transformed into three steps including path planning, path tracking, and motion control of USVs in the paper. A new advanced Dubins-RRT algorithm is proposed for path planning, which improves the capacity of obstacle avoidance and path smoothness level. A virtual target guidance method is used to guide and track the planned path. In addition, a finite-time disturbance observer and a non-singular terminal sliding mode controller are designed to control the autonomous USVs. Observing and estimating the uncertainty terms in the model can ensure the convergence of the tracking error in a finite time. Finally, the feasibility of the designed method is verified through simulation and experimentation.