Abstract: An autonomous underwater vehicle (AUV) obstacle avoidance strategy based on null-space-based behavioral (NSB) approach is designed, aiming at solving dynamic or static obstacle avoidance problem the AUV will encounter while moving to the target in complex underwater environment. Firstly, the AUV overall task moving to the target is decomposed into different subtasks, and the obstacle avoidance subtask is set as the highest priority. As for multi-task control targets, the low-level task vector is projected to the null space of the higher task vector, and the integrated task output is used as the final output function. The low-level task is partially or completely completed while completing the higher task, thereby the mutual conflict between different level targets can be avoided in this way. In order to study the obstacle avoidance strategy for static and dynamic obstacles, the corresponding task functions are designed in accordance with different subtask priorities. The comprehensive output function of AUV motion is deduced and established to ensure that it can avoid different types of obstacles effectively in the process of heading to the target point. The simulation results demonstrate the effectiveness and the feasibility of the proposed method, which could achieve an expected obstacle avoidance effect in complex underwater obstacle environments.

Key words: null-space-based behavioral (NSB) approach; autonomous underwater vehicle (AUV); obstacle avoidance