Underwater acoustic glider

Underwater gliders are buoyancy-driven devices; they alternately reduce and expand displaced volume to dive and climb through the ocean. Gliders carry wings and control their pitch attitude to effectuate a horizontal speed component through the ocean. They turn by rolling their wings or by use of a rudder. Buoyancy control, coupled with hydrodynamic lift is a natural choice for a platform designed to both profile and traverse the stratified ocean where gradients are near vertical and the tilt of surfaces is of key importance. Sensible sampling dictates glide slopes steep compared to isopleths, hence ocean gliders need not attain the shallow slopes of sail planes in the atmosphere. The benefit of gliders is their long range and high endurance for certain types of missions. While typical propeller-driven autonomous underwater vehicles zoom around at a few meters per second for a few hours to cover a few tens of kilometers, gliders are designed to slip through the ocean a fraction of a meter per second for weeks to cover several hundreds of kilometers. Existing gliders run at about 1/2 knot on 1/2 watt. Alaska Native Technologies, LLC, under funding from the Office of Naval Research, has been developing acoustic sensor payloads that can be integrated into underwater gliders and used to demonstrate surveillance and tracking capabilities. In our paper, we describe the acoustic sensor that is being placed within an existing underwater glider (Webb Research's Slocum Glider), we outline the type of demonstrations that are being conducted with the acoustic glider, and we describe the plans for our future work.