Underwater & Out of Sight: Towards Ubiquity in Underwater Robotics
Nicholas Rypkema, Ph.D., 2019
Henrik Schmidt, Advisor
Autonomous underwater vehicles (AUVs) hold the promise of penetrating the ocean environment and uncovering its mysteries, and progress in underwater robotics research has provided vehicles that navigate reliably and operate consistently, giving oceanographers an additional tool for studying the ocean. Unfortunately, their high cost has stifled their democratization. We believe that this is due to two factors. Firstly, reliable AUV navigation has been achieved through the sophisticated Doppler velocity log (DVL)-aided inertial navigation system (INS), which drives up cost, power use and size. Secondly, vehicle deployment is expensive and unwieldy due to their complexity, size and cost, requiring specialized personnel for vehicle operation and maintenance.
The recent development of low-cost, miniature underwater robots provides a solution that mitigates both factors; however, removing the expensive DVL-aided INS means they perform poorly in terms of navigation accuracy. We address this with a novel acoustic system that enables AUV self-localization without requiring a DVL-aided INS or on-board acoustic transmitters. We term this approach Passive Inverted Ultra-Short Baseline (piUSBL) positioning. Our approach has two unique advantages: first, a single beacon lowers cost and enables easy deployment; second, a passive receiver allows the vehicle to be low-power, low-cost and small, and enables multi-vehicle scalability.