Design of a Mobile and Bottom-resting Autonomous Underwater Gliding Vehicle

Most AUVs, and particularly Autonomous Underwater Gliding Vehicles (AUGV), must remain in motion or maintain neutral buoyancy at controlled depths with little or no propulsion. The ability to be both mobile and bottom-resting creates many desirable features in a glider. A mobile to stationary conversion will allow a traditional, bottom mounted sensor platform to be deployed from over the horizon, covertly move into position, and then become a bottom fixture. A central problem is that even gliders, despite their ability to control buoyancy, typically have limited dynamic range of buoyancy and the downward force available is modest. This creates a risk that the glider will be pushed around by the bottom current. Although the present glider design of a cylindrical fuselage with wings and tail could be settled on the bottom, a more suitable design is proposed. A vehicle of lenticular or ellipsoidal shape, having low drag in the horizontal bottom current, can have a rugged exterior to resist abuse if it is pushed around. In order for a bottom-resting vehicle to resist trawls and dredges, it must be capable of attaching itself to the bottom of the ocean. To this effect, an efficient method of anchoring to the bottom must be devised and tested. This paper will cover the design and implementation of a mobile, ellipsoidal glider with bottomresting capabilities. Design issues include internal and external architecture, energy sources, buoyancy drive, anchoring and mooring techniques.