The Virginia Tech self-mooring autonomous underwater vehicle (AUV) is capable of mooring itself on the seafloor for extended periods of time. The AUV is intended to travel to a desired mooring location, moor itself on the seafloor, and then release the mooring and return to a desired egress location. The AUV is designed to be an inexpensive sensor platform. The AUV utilizes a false nose that doubles as an anchor. The anchor is neutrally buoyant when attached to the AUV nose. When the vehicle moors it releases the false nose, which floods the anchor making it heavy, sinking both the anchor and AUV to the seafloor. At the end of the mooring time the vehicle releases the anchor line and travels to the recovery location. A prototype vehicle was constructed from a small-scale platform known as the
Virginia Tech 475 AUV and used to test the self-mooring concept. The final self-mooring AUV was then constructed to perform the entire long duration mission. The final vehicle was tested successfully for an abbreviated mission profile. This report covers the general design elements of the self-mooring AUV, the detailed design of both the prototype and final AUVs, and the results of successful field trials with both vehicles.
Most autonomous vehicles are closely monitored during operation, but a VaCAS team has built a different kind of Autonomous Underwater Vehicle (AUV) in collaboration with the Naval Oceanographic Office (NAVO). This new AUV operates alone and can go long periods of time without communication. Even more unusual, the AUV is self-mooring: it can anchor itself in a precise location of the ocean without drifting.
“This AUV must travel a long distance to a specified location, anchor itself to remain in that location for an extended period of time, then return home when its mission is complete,” says Dan Stilwell, associate professor of electrical and computer engineering, who co-led the team with Wayne Neu, associate professor of aerospace
and ocean engineering.
Six feet long with a diameter of seven inches, the new AUV weighs almost 100 pounds and is more than twice the size of the 475 AUV, which has been used for many applications since 2007.More
The Monterey Bay Aquarium Research Institute (MBARI) has developed a 21-inch (54 cm) diameter docking AUV and companion docking station. This program resulted in four consecutive successful autonomous homing and docking
events in the open ocean, which included downloading data, uploading a new mission plan, recharging the battery, and complete power cycling of the AUV. We describe the design, simulation, and at-sea test of the homing and docking control system.
The utility of present Autonomous Underwater Vehicles (AUVs) is limited by their on-board energy storage capabihty. Research indicates that rechargeable batteries will continue to be the AUV power source of choice for at least the near future. Thus, a need exists in both military and commercial markets for a universal, industry-standard underwater AUV recharge system. A novel solution using a linear coaxial wound transformer (LCWT) inductive coupling mounted on
the AUV and a vertical docking cable is investigated. The docking cable may be deployed from either a fixed docking station or a mobile “tanker AUV”.
A numerical simulation of the simplified system hydrodynamics was created in MATLAB and used to evaluate the mechanical feasibihty of the proposed system. The simulation tool calculated cable tension and AUV oscillation subsequent to the docking interaction. A prototype LCWT couphng was built and tested in saltwater to evaluate the power transfer efficiency of the system. The testing indicated that the surrounding medium has little effect on system performance.
Finally, an economic analysis was conducted to determine the impact of the proposed system on the present military and commercial AUV markets. The recharge system creates substantial cost-savings, mainly by reducing support ship requirements. An effective AUV recharge system will be an important element of the Navy’s net-centric warfare concept, as well as a valuable tool for commercial marine industries.More