Improved dynamic window approach for USV path planning based on COLREGs

In congested waters, when an unmanned surface vessel (USV) is faced with a possible collision with multiple vessels, its navigation has to select a reasonable collision avoidance path within its own kinematic constraints. Therefore, to solve with this complex problem, a collision avoidance method based on the improved dynamic window approach (DWA) is proposed. First, a simple A* algorithm is applied to generate the global path and extract the key nodes. Next, the encounter model of the USV and the encountered ship was established, and a new evaluation rule is introduced on the basis of the COLREGs rule. In response to various encounter situations, the USV will take different actions to select the optimal local navigation path, thereby achieving successful collision avoidance. Upon successfully navigating through local obstacles, the USV seamlessly returns to its original global path. Finally, simulation experiments confirmed the algorithm's effectiveness and feasibility, demonstrating its practical significance.