Three-Dimensional Path Planning of AUV Docking Based on Geometric Constraints

Underactuated autonomous underwater vehicles (AUVs) need to return to a docking station upon completing underwater tasks. However, during the return process, challenges arise due to higher-order differential trajectory characteristics and local accessibility constraints, making them prone to top-down collisions when encountering abrupt changes in seabed topography. To address this issue, this paper proposes a three-dimensional path planning method for AUV docking based on geometric constraints. Firstly, horizontal path planning is conducted using an enhanced Hybrid A* algorithm. Subsequently, vertical path planning is performed based on curve transformations under dynamic constraints. Finally, the three-dimensional path is synthesized. Simulation experiments utilizing actual seabed topographic maps demonstrate that the proposed method reduces heading error by 42%. Furthermore, it maintains a safe altitude in the vertical direction while achieving enhanced smoothness in the tracking curve. Consequently, this approach significantly improves both the efficiency and safety of AUV docking operations.