Short range localization of Autonomous Underwater Vehicles

The melting of Arctic ice and the resulting access provided to previously inaccessible regions of the Arctic Ocean has lead to various Arctic exploratory efforts by a number of nations. Canada is collecting Arctic bathymetry survey data in order to define the extent of its continental shelf in accordance with the United Nations Convention on the Law of the Sea. Supporting the collection of Arctic bathymetry data are two International Submarine Engineering, Explorer class, Autonomous Underwater Vehicles (AUVs). In order to reduce the risk inherent with under-ice AUV operations, Defence Research and Development Canada - Atlantic has designed and built a homing system and a localization system for each of the vehicles. The homing system enables the AUV to find its way to the source of an underwater acoustic signal at ranges in excess of 50 km. In this paper we shall present the localization system, which utilizes a field of acoustic modems allowing the AUV to determine its three dimensional position relative to a reference point. Enhancements to the localization method shall be discussed. These include improvements both at the surface station and the implementation of the algorithm in the vehicle. Lastly, short range localization results from the 2010 Arctic survey trial near Borden Island are presented.