Avoiding obstacles in Underwater Glider Path Planning

Abstract

Underwater gliders are strongly influenced by ocean currents due to their low surge speed. Gliders may drift signif- icantly from their expected trajectories, making path planning a real concern for this type of vehicle, as it may reduce the time taken to reach a given waypoint or save power. In such a dynamic environment it is not easy to find an optimal solution or any such requires large computational resources. In this paper, we present a path planning scheme for this kind of underwater vehicle combining a technique inspired by a variant of the A* algorithm with an optimization process revealing the physical vehicle motion pattern. This method models a glider affected by the ocean current speed and direction, and generates a path according to predefined objectives. The combination of these two techniques allows static or dynamic obstacle avoidance, frequently demanded in coastal environments, with land areas, strong currents, shipping routes, etc. The method can easily be configured and adapted to various optimization problems, in- cluding missions in different operational scenarios. This planner shows promising results in realistic simulations, including ocean currents that vary considerably in time, and provides a superior performance over other approaches that are compared in this paper.