[Objective]This paper develops a multi-stage path planning algorithm for the auto docking oper-ation of an underactuated surface vehicle(USV).As one of the most difficult tasks,docking requires advanced maneuvering skills.Therefore,it is necessary to generate a smooth trajectory in the berthing environment while maintaining control accuracy.[Method]The proposed method introduces a hybrid A* search al-gorithm in the pre-docking stage in which the well-known A* search algorithm is combined with the kinemat-ic state space of the USV using the Reeds-Shepp curves,enabling it to produce sub-optimal paths that guaran-tee kinematic feasibility and low collision risk.For the docking stage,a cubic Bezier curve is introduced to represent the target path.The generated trajectories are then tested in numerical simulations wherein a math-ematical model of a ship with two fixed propellers is established and verified.[Results]The simulation and experimental results show that the path planning and tracking performance of the method are satisfactory.[Conclusion]The proposed path planning method can contribute to automatic ship docking and the de-velopment of smart ships.
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