Andrew Bergey

Small autonomous underwater vehicles (AUVs) that can perceive and explore the environment at low cost are increasingly being deployed for seafloor mapping and biome sensing. A critical sensing ability that many of the larger submarines possess is to perform directional SONAR using arrays of hydrophones to map the environment. Unfortunately, this ability to identify direction-of-arrival (DoA) remains too inaccurate or even infeasible for the small AUVs due to size, weight, and power (SWaP) constraints. This paper presents a new opportunity in augmenting this critical ability using a single hydrophone. This paper presents AMULET, a single hydrophone direction-of-arrival sensing solution in underwater scenarios which leverages acoustic metastructures to introduce directional signatures in the received signal. AMULET’s metastructure takes inspiration from sea shells with a spiral shape that uses air-as-a-metamaterial to augment directional diversity. We further demonstrate how we can extract and compare these directional signatures to estimate the angle-of-arrival across signals of various modulation schemes and different bandwidths as well as complex multipath. Our evaluation in a real-world lake deployment demonstrates a mean error of 4.1° with robustness to distance, across environments, and signal-to-noise ratios.