A versatile acoustic beacon for navigation and remote tracking of multiple underwater vehicles

Abstract

-In this paper, we present a low-cost versatile device developed to support the navigation of autonomous underwater vehicles. Unlike the usual transponders extensively used for LBL acoustic navigation of a single vehicle, this device allows the navigation of multiple vehicles and the remote tracking of their positions, without any extra acoustic signals being transmitted. The navigation beacon has a radio buoy connected to an underwater reconfigurable multi-frequency transponder. A remote tracking station receives data from the buoy and monitors the position of the vehicles in real time. We describe the mechanical, electronic and software modules involved, as well as the tracking algorithm, and we also present experimental data from an operational mission.

Small size AUVs: operation results and new mission concepts 1

“…During the mission, the vehicle motion was monitored using an external tracking system (Cruz et al, 2001). This system computes the position of the vehicle in real time by passively listening to the acoustic signals exchanged between the vehicle and the acoustic navigation beacons.…”

“…To determine its position in the horizontal plane, each vehicle determines its distance to each beacon by sending an interrogation signal, waiting for the transponder reply and measuring the time of flight of the acoustic signals. This method is called spherical navigation and does not require additional signal exchanges, or a communication link, for each vehicle to know the position of the other one in real time (Cruz et al, 2001). The versatile beacons previously developed at the LSTS (Cruz et al, 2001) will be deployed for navigation; these beacons can be programmed to simultaneously listen to several interrogation signals and respond to each one with a different signal.…”

“…This method is called spherical navigation and does not require additional signal exchanges, or a communication link, for each vehicle to know the position of the other one in real time (Cruz et al, 2001). The versatile beacons previously developed at the LSTS (Cruz et al, 2001) will be deployed for navigation; these beacons can be programmed to simultaneously listen to several interrogation signals and respond to each one with a different signal. To avoid channel conflicts, different signals (single tones) are exchanged between each vehicle and each beacon, totalizing eight different signals.…”

MARES — Navigation, Control and On-board Software

“…The digital compass and tilt sensors unit provides data at 20 Hz with accuracies better than 0.5º. The acoustic system is a second generation of multi frequency boards, developed by the Ocean Systems Group, following some excellent results with previous versions (Cruz et al, 2001). These boards are installed on-board the vehicle but also on the acoustic beacons that are deployed in the operation area.…”

Post mission trajectory smoothing for the Isurus AUV

“…These beacons ( Fig. 2) are multi-frequency transponders and were developed at the LSTS [4]. Each beacon can be configured to reply with a signal of given frequency when interrogated by another signal of a possibly different frequency.…”