Recent Advances in Synchronous-Clock One-Way-Travel-Time Acoustic Navigation

Abstract

This paper reports recent results in the development and deployment of a synchronous-clock acoustic navigation system suitable for the simultaneous navigation of multiple underwater vehicles. The goal of this work is to enable the task of navigating multiple autonomous underwater vehicles (AUVs) over length scales of O(100 km), while maintaining error tolerances commensurate with conventional long-baseline transponder-based navigation systems (O(1 m)), but without the requisite need for deploying, calibrating, and recovering seafloor anchored acoustic transponders. Our navigation system is comprised of an acoustic modem-based communication/navigation system that allows for onboard navigational data to be broadcast as a data packet by a source node, and for all passively receiving nodes to be able to decode the data packet to obtain a one-way travel time pseudo-range measurement and ephemeris data. We present field results for a two-node configuration consisting of a surface ship acting as a global navigation aid to a Doppler-aided AUV.

Closed‐loop one‐way‐travel‐time navigation using low‐grade odometry for autonomous underwater vehicles

“…The vehicles used during all of the field trials were Ocean-Server, For timing, a PPSBoard, as discussed previously, 40,41 that incorporates a SeaScan Inc. temperature-compensated crystalline oscillator was integrated for use as a precision reference. The PPSBoard is linked to the vehicle's pulse per second (PPS) signal output from the GPS receiver.…”

“…= * 0.01 (40) and in the re-navigated PF the DR was reduced to 0.05: These methods were developed using data gathered during field trials with two Iver-2 Autonomous Underwater Vehicles (AUVs) and a topside transducer dangled from the R/V Shana Rae in Monterey Bay, CA on September 1 and 2, 2016. These trials were used to evaluate the short term and long term effectiveness of the EKF and PF, the utility of the bias estimator and the use of a topside only or all to all acoustic topology.…”

An overview of AUV algorithms research and testbed at the University of Michigan

“…The VAN framework uses visual perception to augment the onboard dead-reckon navigation capabilities of the unmanned underwater vehicle (UUV). VAN uses a posegraph SLAM framework [3], [4], [9] to incorporate pairwise constraints from overlapping sensor imagery. These constraints is the realtime fusion of "zero-drift" camera measurements with navigation sensor data to close-the-loop on dead-reckoned error.…”

“…In previous work, Eustice et al developed a synchronousclock acoustic modem-based navigation system capable of supporting multi-vehicle ranging [9], [17]. The system consisted of a WHOI Micro-Modem [18], [19] (an underwater acoustic modem developed by Woods Hole Oceanographic Institution (WHOI)) and a low-power stable clock board.…”

“…2. Preliminary OWTT results as reported in [9], [17] for a two node network consisting of an AUV and a surface ship. Shown in blue is the raw dead-reckoned AUV trajectory; in cyan is the GPS-derived ship position; in red is the OWTT fused AUV trajectory; and in green is the (on-surface) GPSmeasured AUV position, which serves as an independent ground-truth.…”