An analysis of real-time terrain aided navigation results from a HUGIN AUV

Terrain aided navigation techniques are attractive for obtaining submerged position fixes for an underwater vehicle. This paper describes results from a real-time terrain navigation system developed for the HUGIN AUV family. The system is a result of previous work on terrain navigation at FFI and has been tested in sea trials on several occasions. In the test described herein, DVL altitude data was used in the terrain navigation system, together with a high quality terrain database. After 5 hours of operation with terrain navigation as the only external position sensor, the horizontal navigation accuracy remained within 5 meters. Offline computations on the same data set show that the terrain navigation algorithms are robust to initial position errors, with the expense of longer convergence times. A comparison of the DVL and map data also revealed a bias that should be investigated further.