Autonomous navigation of the free-swimming vehicle SIRENE

The project DESIBEL, funded by the European Union (MAST-2 programme), included development of the underwater vehicle demonstrator SIRENE. The free-swimming, acoustically, remotely operated vehicle is designed to place and recover deep-sea measuring stations on the sea-floor. The acoustic data link allows one to monitor the vehicle state from the surface and to send guidance commands. The positioning system consists of an acoustic rangemeter working with transponder beacons, and sensors describing attitude and movement of the vehicle. The position estimator realizes two functionalities: 1) to realize selection of consistent sensor measurements; and 2) to compute a position estimate from the validated information. The sensor system as well as the positioning algorithm used are the subjects of this paper. Results from various sea-trials are described and future improvements discussed.