Midpoint-Based Tracking Strategy for a USV to Support Long-Endurance AUV Missions

Autonomous Underwater Vehicles (AUVs) are essential platforms for various underwater missions; however, their limited onboard battery capacity restricts the duration of fully autonomous operations. To overcome this constraint, Unmanned Surface Vehicles (USVs) can be deployed to cooperate with AUVs by providing intermittent charging and communication relay. This paper proposes a simple and effective way-point generation strategy that allows the USV to track an AUV in a more energy-efficient and stable manner. The key idea is to generate a target point for the USV based on the midpoint between the AUV's current position and its closest point on the predefined mission path. This approach smooths out the USV trajectory, avoids unnecessary oscillations, and maintains a communication range between the two vehicles. A MATLAB-based simulation environment was developed to evaluate the performance of the proposed strategy. The results demonstrate that, compared to the conventional Line-of-Sight (LOS) tracking method, the proposed algorithm yields smoother trajectories and reduced maneuvering effort, which are crucial for long-duration missions.