Underwater electric potential measurements using AUVs

Measurements of underwater electric potential (UEP) have several possible applications, including geophysical research, gas and oil exploration, and finding underwater cables and unexploded ordnance. In the present investigation, use of an autonomous underwater vehicle (AUV) to perform measurements of underwater electric potential was explored. An AUV was equipped with a spherical electric field sensor containing three pairs of Ag/AgCl electrodes. A controlled electric field source was mounted on a surface boat for testing. In a shallow saltwater test facility, tests were performed in which the UEP sensor-equipped AUV and surface boat passed one another from opposite directions. UEP measurements acquired by the AUV showed that an ac electric field source at frequencies of 5, 10, and 20 Hz on the surface boat were clearly detected.