Recent developments in the HUGIN AUV terrain navigation system

This paper describes recent developments in the HUGIN AUV terrain navigation system, which uses terrain measurements in order to provide submerged position updates for the main inertial navigation system. In previous versions of the system, a prior bathymetric map database has been required, sometimes restricting the use of the system. To relax this requirement, a real-time map generator has been implemented, such that the vehicle is able to build its own map during the mission. When returning to the mapped area, the system can use this map in order to obtain a terrain navigation fix, thus reducing the uncertainty of the navigation system. Results from a sea trial of the concept are presented, in which the system effectively brings the navigation uncertainty down from more than 50 to about 10 meters. Further results, using the system in the traditional manner with a prior map database, are also included.