LAUSR

An underwater vehicle may utilize underwater transponders (UTs) for navigation in the absence of global navigation satellite system signals. However, the position of each UT must be known by the underwater vehicle. The problem of an autonomous surface vehicle (ASV) optimally planning measurement locations to localize a set of arbitrarily predeployed acoustic UTs is considered. The ASV is assumed to make noisy range measurements to the UTs. A maximum a posteriori estimator is derived to localize the UTs. In addition, a multistep look-ahead (MSLA) ASV optimal measurement location planning (OMLP) strategy is developed. This planning strategy prescribes future multistep measurement locations. A physical interpretation of the proposed planner in the single-step, single transponder case is provided. Simulation results are presented demonstrating the tradeoff between expected localization performance and computational time associated with various look-ahead horizons and travel distances. Experimental results are given illustrating the proposed MSLA OMLP strategy's performance in environments containing one and two UTs. The proposed OMLP strategy is able to localize UTs to within 4 m of their true locations. Additionally, increasing the planning horizon is demonstrated to yield better UT localization at the cost of increased computational burden.