A Small, Long-Range AUV with Flexible Speed and Payload presented by J.G. Bellingham et al. 2010 Ocean Sciences Meeting
A new class of propeller-driven AUV, called the Tethys, has been created specifically to carry biological and chemical sensors for long ranges. The vehicle can support an 8 watt sensor payload for distances in excess of 1,000 kilometers at one meter per second. Operating at a speed of 0.5 meters per second with minimal sensors allows AUV ranges of several thousand kilometers. In addition, by way of a buoyancy engine, the vehicle is capable of trimming to neutral buoyancy and drifting in a low power mode.
The vehicle is small, about 120 kilograms dry weight, and designed to be simple enough for operations by individual laboratories. Tethys provides capabilities falling between existing propeller driven vehicles, which typically have endurances on the order of a day, and buoyancy-driven vehicles (gliders) that can operate for many months. Existing propeller-driven AUVs are optimized around comparatively power-intensive payloads and require logistical support from ships, which increases operational costs. Gliders are designed to carry a minimal sensor suite for as long as possible. While their endurance reduces logistical costs, they can be challenged by currents and have limited payload capacity.
Tethys development focused on combining the merits of propeller-driven and buoyancy driven vehicles, as well as adding some new features such as the drift capability.
MBARI researchers test the LRAUV in the test tank. Move cursor over video to access media controls.
Detailed diagram of the Tethys
Vehicle travels at high speed (~one meter per second) to station A 500 kilometers offshore, and back.
Tethys transits at low speed (0.5 meters per second) to standby location, e.g. station A, adjusts its buoyancy to drift at depth, periodically surfaces, updates its location, communicates with shore, and transits back to station A unless an event detected or it commanded otherwise. On detection of an event, the Tethys transits to the desired location and conducts a survey, and returns to shore, possibly in low-speed mode.
Near-term Tethys Goals
- Travel over 1,000 kilometers at approximately one meter per second with sensors drawing eight watts
- Cover more than 3,000 kilometers with minimal sensors and slow speeds (0.5 meters per second).
- Travel from Monterey Bay, California, to as far as the state of Hawaii of the United States, which would be an approximate distance of 3,868 kilometers.
The information above is from the following reference:J.G. Bellingham, B. Hobson, M. A. Godin, B. Kieft, J. Erikson, R. McEwen, C. Kecy, Y. Zhang, T. Hoover, and E. Mellinger, “A Small, Long-Range AUV with Flexible Speed and Payload,” Ocean Sciences Meeting, Abstract MT15A-14, Portland, OR, February 2010.
Development of the propulsion system was supported by the Office of Naval Research (ONR) under grant N000140210856.