An autonomous energy harvesting station-keeping vehicle for Persistent Ocean Surveillance

The Johns Hopkins University Applied Physics Laboratory developed an autonomous sailing vessel for persistent ocean surveillance. The unmanned autonomous surface vehicle is capable of extracting wind, water turbine, and solar energy from the local environment for long-term station-keeping as part of DARPA´s Persistent Ocean Surveillance Program. The vehicle is capable of withstanding a 1 m/s (2-kt) current and varying littoral sea states to maintain a specified watch radius. The unmanned sailing vehicle uses an autonomously controlled sail and auxiliary thruster that are integrated with GPS, an anemometer (wind speed and direction), three-axis accelerometers, and compass to allow for station-keeping. An initial prototype was designed and developed in 2005, culminating in an at-sea station-keeping demonstration in March 2006. The prototype was successful in station-keeping under sail power 91% of the 24 hour demonstration period. A second-generation prototype that incorporates Iridium communications, solar cells, and an acoustic sensor was designed, developed and tested. Results from the testing demonstrations of the initial and the second generation prototypes will be discussed.