Advanced AUV Navigation and Operation towards Safer and Efficient Near-Bottom Survey

In this paper, two our new approaches for AUV (autonomous underwater vehicle) navigation and their results of field applications are presented. The first approach is for the simultaneous deployment and operation of multiple AUVs. We present the basic concept and outline of our approach related to the navigation, the launch and recovery, the underwater acoustic communication and positioning, and the emergency responses required for operating multiple AUVs with safety and efficiency. Results of hydrothermal field survey mission conducted by deploying multiple vehicles are also presented. The second approach is the navigation of depth-based optimal waypoint following that achieves a safe near-bottom dive of a cruising AUV over a steep and rugged terrain. An optimization algorithm based on gradient descent search (GDS) derives optimal waypoint set accomplishing minimum-altitude dive of a vehicle over a given terrain while satisfying the avoidance of bottom collision.