Metal Detector Signal Imprints of Detected Objects

Humanitarian demining missions are activities in which an operator safety and time consumption are key issues. To increase a discrimination ability of ATMID metal detector, which we have been using, we extended the capability of the detector with mounting inertial measurement unit (IMU) supplemented by two optical distance sensors on the detector head. That enabled us to perform dead reckoning based on accelerations and angular rates measured by IMU in all three axes. Optical distance sensors have been used for compensation purposes and an initial distance measurement. Our main aim was to interconnect magnetic imprint sensed by the detector with precise localization of its head, which led to imprint size estimation as well as its position. Due to low-cost micro-electro-mechanical system (MEMS) based IMU implementation we have had to deal with unstable dead reckoning outcomes. For this reason we used our designed complex magnetic markers (CMMs) which demarked a searched area plus provided us with precise positioning at its both edges. The main contribution of this paper is in the study and identification of CMM magnetic imprints characteristics and their differences related to various aspects of CMM usage during demining procedure and its conditions. The characteristics of CMMs have been studied and analyzed according to several laboratory experiments and results are presented.