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Magnetic position detection system

  • US 9,459,087 B2
  • Filed: 03/05/2013
  • Issued: 10/04/2016
  • Est. Priority Date: 03/05/2013
  • Status: Active Grant
First Claim
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1. A magnetic position detection system comprising:

  • a magnetic target object,an array of magnetometric sensors for detecting the magnetic field from the target object in a detection space, anda data processor for receiving magnetic field measurements from the array of magnetometric sensors and calculating the position of the target object relative to the array,the data processor being adapted to detect whether or not the target object is present in the detection space by;

    fitting a magnetic field model to the magnetic field measurements by minimising differences between the magnetic field model and the magnetic field measurements, determining remaining differences between the fitted magnetic field model and the magnetic field measurements, and determining from the remaining differences whether or not the target object is present in the detection space,wherein the magnetic field sensors and data processor are adapted to conduct periodically a background field measurement process comprising determining whether the target object is present in the detection space, and, if it is not present, storing the measurements as background measurements, and wherein the magnetic field sensors and data processor are further adapted to conduct a target object position sensing process following a determination that the target object is present in the detection space, the target object position sensing process comprising the steps of correcting the magnetic field measurements for a background magnetic field by reference to the stored background measurements and fitting the magnetic field model to the corrected magnetic field measurements to perform said calculation of the position of the target object relative to the array.

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