Precision Geolocation of Active Electromagnetic Sensors Using Stationary Magnetic Sensors

Abstract

Unexploded ordnance (UXO) detection and discrimination is currently performed using mobile electromagnetic induction (EMI) technologies, combined with sophisticated analysis algorithms. Accurate position information for the collected EMI data is essential for success in identifying UXO items. CSIRO Materials Science and Engineering and Sky Research have investigated the feasibility of using the magnetic field produced by an EMI-based UXO detection cart system as a means to accurately locate the position and optionally the tilt of the cart. Using a full tensor gradiometer constructed from fluxgate vector magnetometers; the gradient produced by a cart within 10 m of the instrument was estimated. Three techniques were implemented and compared for determining the position of the cart based on the gradient estimate. We were able to locate the position of the cart to within 0.20 m of its true location at distances of up to 9 m. Accurate tilt information was also demonstrated. We were limited by a noisy acquisition system, and believe improvements could be made to increase the accuracy of the positioning system.