Inversion of the Magnetic Polarisability Tensor at a Single Frequency from Walk-through Metal Detector Measurements

Liam A Marsh, Christos Ktistis, Ari Järvi, David Armitage, Anthony Peyton

    Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

    53 Downloads (Pure)

    Abstract

    A tomographic metal detection and characterisation system has been designed and built with the intention of recovering detailed information about magnetic and/or conductive objects within the detector space. This information is gathered as a result of a “walk-through” scan of a candidate in the same manner as would be expected at a typical security metal detector archway. Following the passage of the candidate, the system uses measurements from an array of coils to calculate the polarisability tensor, which is considered to describe the low frequency electromagnetic characteristic of a small metallic object when it interacts with a magnetic field. The tensor is known to vary according to the excitation frequency of the applied magnetic field, however in this system only a single frequency measurement is considered. In addition to the magnetic polarisability dyadic tensor the position of the perturbation is also determined as a product of the inversion algorithm.The inversion algorithm used in this paper is based on the implementation of a model which is calculated by the multiplication of the transmit and the receive magnetic field strength vectors with the magnetic polarisability dyadic. The inversion algorithm seeks to minimise the error between the actual measurements and the simulated measurements through the modification of an estimated object tensor and the variation in estimated object location.The system has been tested and is capable of inverting object tensors with
    Original languageEnglish
    Title of host publicationhost publication
    Publication statusPublished - 26 Mar 2012
    Event6th International Symposium on Process Tomography - Cape Town, South Africa
    Duration: 26 Mar 201228 Mar 2012

    Conference

    Conference6th International Symposium on Process Tomography
    CityCape Town, South Africa
    Period26/03/1228/03/12

    Keywords

    • Magnetic polarisability tensor, Inversion, Walk-through metal detection, Electromagnetic security, Screening systems

    Fingerprint

    Dive into the research topics of 'Inversion of the Magnetic Polarisability Tensor at a Single Frequency from Walk-through Metal Detector Measurements'. Together they form a unique fingerprint.

    Cite this