Automatic data collection algorithm for 3D magnetic field calibration with reduced memory requirements
First Claim
1. A non-transitory program product for calibrating a magnetic compass, the program product comprising a processor-readable medium on which program instructions are embodied, wherein the program instructions are operable, when executed by at least one programmable processor coupled to the magnetic compass, to cause the magnetic compass to:
- collect a plurality of magnetic field samples while the magnetic compass is rotated;
select a number of the plurality of magnetic field samples as validated magnetic field samples, wherein the selecting of the validated magnetic field samples is done by recursively comparing the angle between each of the magnetic field samples and all previously validated magnetic field samples to ensure the selected magnetic sample being validated is at least a minimum separation angle apart from all previously validated magnetic field samples; and
compute calibration coefficients from the selected validated magnetic field samples, wherein the computed calibration coefficients are used to calibrate the magnetic compass.
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Abstract
A magnetic compass comprising a magnetometer for taking readings of a magnetic field and a processing unit that calibrates the magnetic compass is provided. The processing unit is configured to validate a predetermined number of magnetic field samples and calculate calibration coefficients from the validated magnetic field samples. Each validated magnetic field sample is at least a minimum separation angle apart from every other validated magnetic field sample.
17 Citations
20 Claims
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1. A non-transitory program product for calibrating a magnetic compass, the program product comprising a processor-readable medium on which program instructions are embodied, wherein the program instructions are operable, when executed by at least one programmable processor coupled to the magnetic compass, to cause the magnetic compass to:
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collect a plurality of magnetic field samples while the magnetic compass is rotated; select a number of the plurality of magnetic field samples as validated magnetic field samples, wherein the selecting of the validated magnetic field samples is done by recursively comparing the angle between each of the magnetic field samples and all previously validated magnetic field samples to ensure the selected magnetic sample being validated is at least a minimum separation angle apart from all previously validated magnetic field samples; and compute calibration coefficients from the selected validated magnetic field samples, wherein the computed calibration coefficients are used to calibrate the magnetic compass. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A magnetic compass, comprising:
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a magnetometer for taking readings of a magnetic field; and a processing unit that calibrates the magnetic compass, wherein, during calibration, the processing unit is configured to; select a number of magnetic field samples as validated magnetic field samples, wherein the magnetic field samples are obtained while rotating the magnetic compass, and wherein each selected validated magnetic field sample is at least a minimum separation angle apart from every other selected validated magnetic field sample; and calculate calibration coefficients from the selected validated magnetic field samples. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A device for calibrating a magnetic compass, comprising:
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a functional circuit coupled to the magnetic compass that uses heading information; a magnetometer for taking readings of a magnetic field; a processing unit that calibrates the magnetic compass based on a plurality of magnetic field samples collected while rotating the magnetic compass, wherein the processing unit is configured to; select a number of the collected plurality of magnetic field samples as validated magnetic field samples, wherein each selected validated magnetic field sample is at least a minimum separation angle apart from every other selected validated magnetic field sample, calculate calibration coefficients from the selected validated magnetic field samples, wherein the calculated calibration coefficients are used to compensate the readings of the magnetic field by the magnetometer; and a memory for storing the calibration coefficients; and a display device. - View Dependent Claims (17, 18, 19, 20)
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Specification