Method and apparatus for fast magnetometer calibration
First Claim
1. A method for fast calibration of a magnetometer from natural motion with little space coverage, the method comprising the steps of:
- a) obtaining earth magnetic field information in a region where the magnetometer is located, the magnetic field information to be used as reference values;
b) collecting magnetometer readings; and
c) providing at least one processor configured to;
i) obtain an absolute heading from a source of absolute navigational information that is different from the magnetometer, the absolute heading to be used as a second reference; and
ii) make a determination of sufficient space coverage using at least the absolute heading, wherein the determination of sufficient space coverage comprises at least angular separation values in a heading domain; and
d) based at least in part on the determination of sufficient space coverage made by the at least one processor, calibrating the magnetometer by calculating calibration parameters when the sufficient space coverage is available, wherein the calculation of calibration parameters comprises calculating error parameters in the magnetometer readings using a relationship between at least the earth magnetic field information, the magnetometer readings, the absolute heading from the source of absolute navigational information that is different from the magnetometer, and the error parameters in the magnetometer readings.
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Accused Products
Abstract
A method and apparatus for fast magnetometer calibration with little space coverage is described herein. The present method and apparatus is capable of performing both 2-dimensional (2D) and 3-dimensional (3D) calibration for a magnetometer (magnetic sensor) and calculating calibration parameters. The present method and apparatus does not need the user to be involved in the calibration process and there are no required specific movements that the user should perform. The present method and apparatus performs magnetometer calibration in 2D or 3D depending on the natural device movements whatever the application that the magnetometer is used in.
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Citations
22 Claims
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1. A method for fast calibration of a magnetometer from natural motion with little space coverage, the method comprising the steps of:
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a) obtaining earth magnetic field information in a region where the magnetometer is located, the magnetic field information to be used as reference values; b) collecting magnetometer readings; and c) providing at least one processor configured to; i) obtain an absolute heading from a source of absolute navigational information that is different from the magnetometer, the absolute heading to be used as a second reference; and ii) make a determination of sufficient space coverage using at least the absolute heading, wherein the determination of sufficient space coverage comprises at least angular separation values in a heading domain; and d) based at least in part on the determination of sufficient space coverage made by the at least one processor, calibrating the magnetometer by calculating calibration parameters when the sufficient space coverage is available, wherein the calculation of calibration parameters comprises calculating error parameters in the magnetometer readings using a relationship between at least the earth magnetic field information, the magnetometer readings, the absolute heading from the source of absolute navigational information that is different from the magnetometer, and the error parameters in the magnetometer readings. - View Dependent Claims (2, 3, 4, 5, 6, 7, 10, 11)
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- 8. The method of 7, wherein the method further comprises shelving the calibration parameters for future use.
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12. A device comprising:
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a. a magnetometer; and b. a processor, coupled to receive readings from the magnetometer, and operative to perform magnetometer calibration from natural motion with little space coverage, wherein the processor is operative to; i) obtain earth magnetic field information in a region where the magnetometer is located, the magnetic field information to be used as reference values; ii) collect magnetometer readings; iii) obtain an absolute heading from a source of absolute navigational information that is different from the magnetometer, the absolute heading to be used as a second reference; iv) make a determination of sufficient space coverage using at least the absolute heading, wherein the determination of sufficient space coverage comprises at least angular separation values in a heading domain; and v) based at least in part on the determination of sufficient space coverage, calibrate the magnetometer by calculating calibration parameters when the sufficient space coverage is available, wherein the calculation of calibration parameters comprises calculating error parameters in the magnetometer readings using a relationship between at least the earth magnetic field information, the magnetometer readings, the absolute heading from the source of absolute navigational information that is different from the magnetometer, and the error parameters in the magnetometer readings. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification