Research on Local Path Planning for Autonomous Collision Avoidance of USV

While sailing, unmanned surface vehicles (USVs) should avoid both static obstacles and moving ships, and the collision avoidance between two ships should follow COLREGs, which brings challenges to local path planning. This paper proposes a local path planning algorithm based on a three-stage collision avoidance strategy. The three stages correspond to the moving ship is far away, the moving ship is close but has a low risk of collision, and the moving ship is close and has a high risk of collision, respectively. In the first stage, a dynamic obstacle avoidance maneuverable range and an improved dynamic window approach are proposed, and the environmental influence is introduced to improve collision avoidance efficiency. In the second and third stages, this paper combines velocity obstacle and COLREGs to design the collision avoidance algorithm between USV and moving ship. In order to select the optimal dynamic target point, VO limit is introduced in the second stage, port limit and starboard scoring mechanism are introduced in the third stage. The experimental results show that the algorithm can realize the collision avoidance of USV effectively based on COLREGs.