Passive Inverted Ultra-Short Baseline Positioning for a Disc-Shaped Autonomous Underwater Vehicle: Design and Field Experiments

Underwater positioning is critical to autonomous underwater vehicles (AUVs) for navigation and geo-referencing. The rapid attenuation of the electromagnetic wave in the underwater environment prevents the use of traditional positioning methods such as the Global Positioning System, whereupon acoustic methods like ultra-short baseline (USBL) positioning systems play an important role in AUV navigation. However, the high cast and complexity of classical USBL systems have stifled the democratization of these technologies, which leads to a new method called passive inverted ultra-short baseline (piUSBL) positioning. In a typical piUSBL system. a single beacon is placed at a reference point, periodically broadcasting a positioning signal. A passive USBL receiver, time-sy nchronized to the beacon, is mounted on an AUV to get one-way travel-time (OWTT) slant range and azimuth estimates. The passive nature of the receiver means the system is inexpensive, low-power, and lightweight. Particularly, the omnidirectional broadcasted signals offer a feasible solution for concurrent multi-AUV navigation. This letter demonstrates a full-stack design and development of a piUSBL, positioning system, and presents evaluations of the accuracy and reliability of the system through a series of experiments. More significantly, a successful sea trial of a disc-shaped AUV outfitted with our piUSBL was conducted in the South China Sea.

Automated summary

Underwater positioning is crucial for navigation and geo-referencing of AUVs. Traditional methods like GPS are not feasible in underwater environments, leading to the importance of acoustic methods like USBL positioning systems. However, the high cost and complexity of classical USBL systems hinder their widespread adoption, which is addressed by the piUSBL positioning method.