Underwater mobile docking of autonomous underwater vehicles

Mobile Underwater Docking is a forward looking objective for AUV users to conduct a remotely controlled launch and recovery of a REMUS 100 AUV from a surface vessel platform. The final configuration would include a recovery onto the surface vessel, a download of data and battery charge after recovery and an upload of mission tasking for a subsequent sortie. This paper only covers the docking and undocking phases. Hydroid's concept for this system involves the REMUS 100 intercepting and mating with a submerged towed docking cone. At the end of the REMUS 100's sortie the vehicle goes into a submerged circular loiter. A transducer on the REMUS 100 is used to interrogate a transponder attached to the launch and recovery docking cone. As the surface vessel approaches the rendezvous location the REMUS 100 refines the position of the mobile underwater dock using the DUSBL system located in its nose and calculates an intercept course. The REMUS 100 approaches the towed docking cone and enters the docking cone. The docking cone and vehicle will lock together and once sensed by the vehicle the surface vessel would be informed via acoustic comms. Woods Hole Oceanographic and Hydroid have developed and delivered stationary (fixed) underwater docks for AUV battery charge and data download capabilities as well as vehicles configured for docking. Typically a fixed design using a high frequency transponder for navigational guidance provides superior performance results since the target is not in motion and the variables are limited to the acoustic guidance factors. This was the basis for the current design. The underwater capture docking system, consisting of a depressor and capture system and a transponder, is intended to be towed behind a surface vessel. A REMUS 100 vehicle is outfitted with a LBL transducer, a DUSBL and a latching device assembly. The DUSBL is mounted in the nose and is used for tracking the range and bearing to the dock. Previous DUSBL use was confined to homing to a stationary transponder where the transponder's depth and position were known to the REMUS vehicle. For this application the transponder's position is initially unknown and constantly changing. In addition, the speed and heading of the docking transponder must be estimated in order to intercept and perform docking maneuvers.