Distortion-immune position tracking using redundant measurements
First Claim
1. A method for tracking a position of an object in a working volume, comprising:
- using a field sensor associated with the object to measure field strengths of magnetic fields generated by two or more field generators, the magnetic fields generated by two or more field generators defining a working volume, wherein a measurement of at least one of the field strengths is subject to a distortion;
calculating raw location coordinates of the object responsively to the measured field strengths, the raw location coordinates of the object defining rotation invariant location coordinates of the object;
determining corrected location coordinates of the object by applying a coordinate correcting function to the rotation-invariant location coordinates to adjust a relative contribution of each of the measured field strengths to the corrected location coordinates responsively to the distortion in the measured field strengths according to a plurality of sub-volumes of the working volume,wherein applying the coordinate correcting function comprises identifying one or more distortion-contributing elements responsively to the measured field strengths and giving lower weight to measured field strengths associated with the one or more distortion-contributing elements.
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Abstract
A method for tracking a position of an object includes using a field sensor associated with the object to measure field strengths of magnetic fields generated by two or more field generators, wherein a measurement of at least one of the field strengths is subject to a distortion. Rotation-invariant location coordinates of the object are calculated responsively to the measured field strengths. Corrected location coordinates of the object are determined by applying to the rotation-invariant location coordinates a coordinate correcting function so as to adjust a relative contribution of each of the measured field strengths to the corrected location coordinates responsively to the distortion in the measured field strengths.
25 Citations
26 Claims
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1. A method for tracking a position of an object in a working volume, comprising:
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using a field sensor associated with the object to measure field strengths of magnetic fields generated by two or more field generators, the magnetic fields generated by two or more field generators defining a working volume, wherein a measurement of at least one of the field strengths is subject to a distortion; calculating raw location coordinates of the object responsively to the measured field strengths, the raw location coordinates of the object defining rotation invariant location coordinates of the object; determining corrected location coordinates of the object by applying a coordinate correcting function to the rotation-invariant location coordinates to adjust a relative contribution of each of the measured field strengths to the corrected location coordinates responsively to the distortion in the measured field strengths according to a plurality of sub-volumes of the working volume, wherein applying the coordinate correcting function comprises identifying one or more distortion-contributing elements responsively to the measured field strengths and giving lower weight to measured field strengths associated with the one or more distortion-contributing elements. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A system for tracking a position of an object in a working volume, comprising:
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two or more field generators, which are arranged to generate respective magnetic fields in a vicinity of the object, the respective magnetic fields generated by two or more field generators defining a working volume; a field sensor associated with the object, which is arranged to measure field strengths of the magnetic fields, wherein a measurement of at least one of the field strengths is subject to a distortion; and a processor, which is arranged to calculate raw location coordinates of the object responsively to the measured field strengths, the raw location coordinates of the object defining rotation invariant location coordinates of the object, and to determine corrected location coordinates of the object by applying a coordinate correcting function to the rotation-invariant location coordinates to adjust a relative contribution of each of the measured field strengths to the corrected location coordinates responsively to the distortion in the measured field strengths according to a plurality of sub-volumes of the working volume, wherein applying the coordinate correcting function identifies one or more distortion-contributing element responsively to the measured field strengths, and gives lower weight to measured fields strengths associated with the one or more distortion-contributing elements. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification