Modeling the response of electromagnetic induction sensors to inhomogeneous magnetic soils with arbitrary relief

Pascal Druyts, Yogadhish Das, Christophe Craeye, Marc Acheroy

Research output: Contribution to journalArticlepeer-review

Abstract

A general model to compute the response of an electromagnetic induction sensor to a magnetic soil, in both time and frequency domains, is developed. The model requires modest computational resources and can be applied to arbitrary soil inhomogeneities and relief, and to arbitrary sensor coil shapes, orientations, and positions. Central to the model is the concept of a head sensitivity map, which can be used to characterize the sensor head as a function of the shape, size, and position of the sensor coils. Two further concepts related to the head sensitivity are presented, which are the zero equisensitivity surface and the volume of influence. We demonstrate that these concepts aid the understanding of the detector behavior. The general model is based on the Born approximation, which is valid if the soil magnetic susceptibility is sufficiently small. A simpler model, which is only valid for homogeneous half-space soils but does not require the Born approximation, is also developed. The responses predicted by both models are shown to be in good agreement with each other and also with available analytic solutions. Comparing the two models also enabled an expression for the error incurred when using the Born approximation to be established. We shown that, for most soils of relevance to mine clearance, the corresponding error is negligible.

Original languageEnglish
Article number4806100
Pages (from-to)2627-2638
Number of pages12
JournalIEEE Transactions on Geoscience and Remote Sensing
Volume47
Issue number8
DOIs
Publication statusPublished - Aug 2009

Keywords

  • Born approximation
  • Electromagnetic induction (EMI)
  • Humanitarian demining
  • Magnetic susceptibility
  • Metal detector (MD)
  • Reciprocity
  • Sensitivity map

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