A motion planning method for an AUV

The authors have been developing an underwater vehicle "Umihico" that autonomously plans and executes given missions. This paper discusses the problem of finding an optimal motion plan for an AUV. The proposed motion planning algorithm is divided into two steps, the global path planning and the local motion planning steps. In the global path planning step, we first define a connectivity graph to evaluate the cost of each path class. Next we apply the Dijkstra's algorithm or the all-pairs cost algorithm to the graph to find the optimal (minimum cost) path class. In the local motion planning step, a smooth path segment which connects two configurations in the optimal path class in each region is computed. If there are any obstacles, the local motion planning algorithm will plan and execute an obstacle avoiding action. The effectiveness and robustness of the solution algorithm are verified through simulation.