A Two-stage Coverage Path Planning Compliant with the Kinematic Constraints of USVs

The existence of omitted areas is unacceptable in coverage missions such as maritime search and military reconnaissance. Therefore, it is crucial to plan a path that can guarantee the full coverage of the mission area and conform to the kinematic characteristics of Unmanned Surface Vehicles (USVs). To achieve this objective, this paper proposes a two-stage coverage path planning algorithm aimed at optimizing coverage paths of underactuated USVs. In the first stage, the USV is modeled as a particle to facilitate path planning, and an improved Direction Highest Priority First (DHPF) coverage path planning algorithm is proposed to minimize collision risks for USVs during turns near obstacles. In the second stage, two kinematic constraints, turning radius, and safety distance, are incorporated into the USV model, and a multi-strategy switching framework is devised to tackle planning challenges associated with different types of paths. Specifically, an improved Hybrid A-star path planning algorithm with a variable step size is proposed to minimize both the path length and search time, and a backward mechanism is introduced to ensure full coverage of the area when forward turning conditions of the USV cannot be satisfied. The simulation results demonstrate the effectiveness of the proposed coverage path planning algorithm.