A Hierarchical Control Scheme for Trajectory Tracking USVs in Environments With Disturbances and Dynamic Obstacles

In this paper, a hierarchical control scheme for trajectory-tracking unmanned surface vehicles (USVs) is proposed and tested. The proposed control scheme is capable of avoiding dynamic obstacles under wind and sea current disturbances. In the controller hierarchy, a waypoint guidance law integrated with a runtime obstacle avoidance algorithm, a next-point generation algorithm for the waypoint guidance law, and a linear quadratic regulator controller together with a yaw autopilot are designed. The performance of the proposed hierarchical controller scheme is evaluated in environments including static and dynamic obstacles of variable sizes and speeds. Furthermore, the tests include the wind and sea current disturbances. The paper aims to address the gap in the literature on runtime dynamic obstacle avoidance of USVs in mild environmental conditions. The superiority of the proposed controller design is demonstrated in various scenarios, where the vehicle avoids the obstacles and reaches the final waypoint with satisfactory path tracking performance under the disturbances and dynamic characteristics of the obstacles.