Self-localization of a distributed array of small autonomous underwater platforms using a shipping source of opportunity

Using a network of autonomous underwater platforms as a distributed coherent sensing array requires precise positioning of each sensor node. Here, a self-localization (i.e., totally passive) method using only acoustic sources of opportunity (such as surface vessels) to locate the mobile sensor nodes is presented as an alternative to conventional active short or long baseline systems. Existing underwater self-localization methods have mainly been developed for mobile platforms equipped with time-synchronized hydrophones and rely only on the time difference of arrivals between multiple pairwise combinations of the mobile hydrophones as inputs for a complex non-linear inversion procedure. Instead, we present a three-dimensional self-localization method using a linear least square formulation between mobile time-synchronized underwater platforms equipped with a compact directional hydrophone array based on their acoustic recordings of a distant surface vessel and their inertial navigation systems measurements. The influence of acoustic refraction and environmental variability on the performance of this self-localization method is investigated using deep water acoustic data collected near the Atlantis II seamounts in the Northwest Atlantic by two Wave Gliders instrumented with underwater towed acoustic modules located above and below the sonic layer depth for separation distance up to a few kilometers. Work sponsored by ONR.