Toward autonomous mapping with AUVs - line-to-line terrain navigation

In autonomous mapping surveys the autonomous underwater vehicle (AUV) cannot rely on receiving position aiding from a surface vehicle or any other external infrastructure. The AUV can however use any payload sensor to restrict the position error drift in the navigation system. In this paper we consider using the bathymetric sensor in line-to-line terrain navigation. Terrain navigation will limit position error growth, and also ensure enough overlap between the lines such that the survey area is covered. We show that sparse map coverage from a line of bathymetry leads to a bias when used in a straightforward implementation of the point mass filter terrain navigation algorithm, and we develop a modification to the algorithm that handles this robustly. The algorithm achieves good performance when tested off-line on real data from a HUGIN AUV equipped with the HISAS 1030 interferometric synthetic aperture sonar.