Joint Positioning and Navigation Aiding Systems for Multiple Underwater Robots

This paper proposes a new joint positioning and navigation aiding system for multiple underwater robots. In the scenario adopted, each submersed target carries a pinger that emits acoustic signals periodically, as determined by a low precision clock. The targets are tracked from the surface by a set of buoys equipped with acoustic hydrophones/projectors, GPS receivers, and electronic circuitry that measures the times of arrival of the acoustic signals emitted by the pinger. The buoys at surface, synchronized with the GPS timing, emit periodically distinctive signals that the underwater vehicles can use as aids to their onboard navigation systems. In the case where buoys drift away more than a pre-specified distance from their nominal positions, coded signals are emitted. The scheme proposed allows for the performance in the tracking and navigation systems to be independent from the number of targets present in the scenario of operation. Simulation results are presented to assess the performance of both the positioning tracker and a simplified onboard integrated navigation system.