Collaborative AUV Localization and Tracking of an Underway Ship with Adaptive Pinging and a Planner for Trilateration

The efficacy of 3 collaborative autonomous under-water vehicles (AUV) to track a dark ship is studied in a scenario where the ship has entered a marine protected area through a choke point. This is performed in simulations. The objective is to quantity the advantage of mobile transducers over traditional moored long baseline (LBL) transponders. An underwater environment with a constant sound velocity profile captures the one-way travel time inter-AUV communications as well as the two-way travel time for AUVs ranging the ship. The novel contributions include an assessment of the ship localization error given the self-localization error of the three AUVs and their range measurement uncertainty. Another contribution is an adaptive ping strategy, which potentially gives more accurate ship localization by scheduling the pings to arrive simultaneously at the ship. The third contribution is a collaborative AUV mission planner which strives to increase the range that the 3 AUVs can trilaterate the ship over. The results show that the adaptive ping strategy and the collaborative AUV mission planner are effective in reducing ship localization error. With these encouraging results, future work includes a refined environment model that integrates BELLHOP and considers environmental and range dependent communications.