Cooperative Navigation for Autonomous Underwater Vehicles

Alexander Bahr, Ph.D., 2009
John Leonard, Advisor

Self-localization of an underwater vehicle is particularly challenging due to the absence of GPS reception or features at known positions that could be used for position computation. This typically requires the pre-deployment of a set of beacons. This thesis examines the scenario in which the members of a group of AUVs exchange navigation information with one another so as to improve their individual position estimates.

We describe how the underwater environment poses unique challenges to vehicle navigation and how cooperation can improve the performance of self-localization. We also address the constraints of the communication channel and the effect that these constraints have on the design of cooperation strategies. The classical approaches to underwater self-localization of a single vehicle are presented. We then examine how methods used for cooperating land-vehicles can be transferred to the underwater domain. An algorithm for distributed self-localization is proposed. We also address how correlated position estimates of cooperating vehicles can lead to overconfidence in individual position estimates. Finally, key to any successful cooperative navigation strategy is the incorporation of the relative positioning between vehicles. A distributed algorithm for the dynamic positioning of vehicles is proposed.