Improving Underwater Navigation and Docking with Three-Dimensional Sonar

W.R. Woodward, R. Webb, R. Kahrs Hansen, B. Cunningham, D.J. Weber, R.F. Weingaertner

Abstract:	Until recently, obtaining a position fix while underwater was difficult. However, a new 3D sonar technology offers position fixes with the accuracy of GPS. This sonar can accurately measure the position of an underwater object relative to own ship. The geospatial position of the vehicle is calculated from the position of the vehicle with respect to a fixed underwater navigation aid. The position information is supplied to the INS as a position fix, increasing the position accuracy of the INS. Essentially, the INS potentially has almost the same positional accuracy underwater as it would on the surface receiving GPS position fixes. The ability to obtain an underwater position fix can greatly extend the time a vehicle with a Circular Error Probable (CEP) of 10 meters can stay underwater, without surfacing or having an antenna surface to obtain a GPS position fix. In an environment where regular 3D sonar position fixes can be obtained, the vehicle would not have to surface for a GPS position update. Eliminating the need to obtain a GPS position fix can extend the time the vehicle has to perform its mission. Docking an underwater vehicle can present some unique challenges, especially in murky water where a video camera has little or no visibility. The 3D sonar can look through murky water and provide high-resolution images. These images can be used to guide the vehicle during docking when the camera has limited visibility. They can also be used as an additional sensor working in parallel with the camera.
Published in:	Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009) September 22 - 25, 2009 Savannah International Convention Center Savannah, GA
Pages:	702 - 708
Cite this article:	Woodward, W.R., Webb, R., Hansen, R. Kahrs, Cunningham, B., Weber, D.J., Weingaertner, R.F., "Improving Underwater Navigation and Docking with Three-Dimensional Sonar," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 702-708.
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