Dual accelerometer vector sensor mounted on an autonomous underwater vehicle (AUV) - Experimental results

Abstract

In seismic geo-acoustic exploration, the use of ships equipped with long streamers is of major concern due to the complexity of the operations. The European project WIMUST aims to improve the efficacy of actual geoacoustic surveys through the use of AUVs towing short streamers. A Dual Accelerometer Vector Sensor (DAVS) was developed in order to complement the streamer's data, allowing for the reduction of their size and facilitating the operation of the WiMUST distributed configuration. Each DAVS consists of two tri-axial accelerometers and one hydrophone aligned along a vertical axis. This configuration has the ability to cancel or significantly attenuate the direct and the surface reflection paths, which are undesirable in seismic imaging. Calibration tests with the DAVS have already been performed; this paper presents experimental results on the estimation of azimuthal directions when the DAVS is in motion. Signals in the 1-2kHz band were emitted by a source deployed in a shallow pond at 1.5m depth and acquired by the DAVS mounted on a MEDUSA class AUV, which was following a pre-programed path with a 0.26m/s nominal speed. The azimuth estimates are coherent with the MEDUSA trajectories even in curved paths where the thruster noise increases.