Map based underwater navigation using a multibeam echosounder

This paper describes a navigation system for underwater vehicles (UV) using bathymetric profiles. The UV localisation by matching a local bathymetry within a reference map aims to avoid the use of transponder-based positioning systems which need a costly preparation. Terrain based navigation concerns, using a vehicle-borne multibeam echosounder, to build a local map of the bottom and to match it to a previously constructed terrain map. Bathymetric image restoration and segmentation are necessary before extracting characteristic points from the two maps. These points are matched by the means of rotational and translational invariant attributes. An iterative algorithm estimates the position and the orientation of the local bathymetry and actualizes the set of matched points, The real time estimation of attribute variances allows the use of probabilistic tools like the Mahalanobis distance (threshold) and the Kalman filter (position estimation).