Low altitude AUV terrain navigation using an interferometric sidescan sonar

In low altitude operations of the HUGIN 1000-MR autonomous underwater vehicle, the footprint of its multibeam echo sounder (EM 3000) becomes small. Terrain navigation depends on terrain variability to be present within the footprint, and becomes less accurate in these scenarios. The problem is addressed by including interferometric sidescan measurements from the on board synthetic aperture sonar (HISAS 1030). Some preliminary results are presented on the comparison of the position accuracy obtained from terrain navigation using each sensor separately, and for the fusion of the two sensors. The comparison is done on co-registered data collected by HUGIN 1000-MR in variable terrain.