Data processing method for an electronic compass system
First Claim
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1. A method of offsetting elliptification and rotation distortion caused by induced magnetism to obtain undistorted heading data values for determining accurate compass headings in an electronic compass used for a vehicle configuration, comprising:
- orienting first and second sense coils of a flux-gate sensor perpendicular to each other in the earth'"'"'s magnetic field;
saturating said first and second sense coils using a drive signal;
measuring an induced voltage in said first and second sense coils induced by said magnetic field;
calibrating said electronic compass for said vehicle configuration for induced magnetism causing said elliptification and rotation distortion by generating first, second, third and fourth linear transform coefficients;
storing said first, second, third and fourth linear transform coefficients in memory;
obtaining first and second distorted heading data values related to said induced voltage in said first and second sense coils;
multiplying said first linear transform coefficient by said first distorted heading data value to obtain a first product using a processor;
multiplying said second linear transform coefficient by said second distorted heading data value to obtain a second product using said processor;
subtracting said second product from said first product to obtain a first transformed heading data point using said processor;
multiplying said third linear transform coefficient by said first distorted heading data value to obtain a third product using said processor;
multiplying said fourth linear transform coefficient by said second distorted heading data point to obtain a fourth product using said processor;
subtracting said fourth product from said third product to obtain said second transformed heading data point using said processor; and
generating a compass heading from said first and second transformed heading data points using said processor.
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Abstract
A method for converting distorted compass data values into corrected data values which employs linear transforms. A linear transform is formulated and programmed into the read only memory of the microcomputer of the electronic compass system. The microcomputer uses the linear transform to transform compass data readings distorted by ferrous metals in the environment of the vehicle into corrected data readings and then uses the corrected data readings to compute headings.
36 Citations
5 Claims
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1. A method of offsetting elliptification and rotation distortion caused by induced magnetism to obtain undistorted heading data values for determining accurate compass headings in an electronic compass used for a vehicle configuration, comprising:
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orienting first and second sense coils of a flux-gate sensor perpendicular to each other in the earth'"'"'s magnetic field; saturating said first and second sense coils using a drive signal; measuring an induced voltage in said first and second sense coils induced by said magnetic field; calibrating said electronic compass for said vehicle configuration for induced magnetism causing said elliptification and rotation distortion by generating first, second, third and fourth linear transform coefficients; storing said first, second, third and fourth linear transform coefficients in memory; obtaining first and second distorted heading data values related to said induced voltage in said first and second sense coils; multiplying said first linear transform coefficient by said first distorted heading data value to obtain a first product using a processor; multiplying said second linear transform coefficient by said second distorted heading data value to obtain a second product using said processor; subtracting said second product from said first product to obtain a first transformed heading data point using said processor; multiplying said third linear transform coefficient by said first distorted heading data value to obtain a third product using said processor; multiplying said fourth linear transform coefficient by said second distorted heading data point to obtain a fourth product using said processor; subtracting said fourth product from said third product to obtain said second transformed heading data point using said processor; and generating a compass heading from said first and second transformed heading data points using said processor. - View Dependent Claims (2, 3, 4, 5)
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Specification