Estimating directional magnetic polarizabilities of metallic objects using planar time-domain electromagnetic induction sensor

摘要

Directional magnetic polarizabilities are intrinsic features of metallic objects, closely related to their geometrical and material properties. They are therefore considered as key parameters for characterization and classification of metallic targets using electromagnetic induction (EMI) sensing. This paper deals with the problem of estimating time-dependent directional magnetic polarizabilities and the location of an obscure metallic target using induced voltage measurements from a planar time-domain (TD) EMI sensor. We present a modeling and parameter estimation methodology, enabling determination of a full time-decay curve of directional magnetic polarizabilities over a specified time window. Performance of the proposed estimation algorithm is evaluated in laboratory environment using our experimental planar TD EMI sensor and three metallic test samples. For a given testing scenario, the algorithm was able to correctly identify dominant magnetic polarizabilities of each target, irrespective of its location. Target positions were estimated with a minimum accuracy of ± 4 mm for x- and y-coordinates, and ± 8 mm for z-coordinates.