Vehicle compass compensation

A vehicular electronic compass system comprising:

• a magneto-responsive sensor assembly for sensing a magnetic field;
• an electronic circuit responsive to said sensor assembly for determining at least one of a magnitude and direction of the Earth magnetic field, said electronic circuit collecting a plurality of data points relative to a coordinate system associated with the vehicle, each of said data points having at least two components relative to said coordinate system, said electronic circuit averaging at least one component of at least two of said data points to determine an estimated value of the Earth magnetic field along at least one axis of said coordinate system, thereby calculating an estimated offset of the Earth magnetic field, said electronic circuit adjusting a directional heading output to account for the offset;
• and
• an electronic display coupled with said electronic circuit for displaying a direction of the Earth magnetic field.

A vehicular electronic compass system, comprising:

• a magneto-responsive sensor assembly for sensing a magnetic field;
• an electronic circuit responsive to said sensor assembly for determining at least one of magnitude and direction of the Earth magnetic field, said electronic circuit collecting data points, determining from the collected data points an offset value of the Earth magnetic field, and adjusting a directional heading output of said sensor assembly to account for said offset value;
• said electronic circuit including an extended range calibration function identifying a change in magnetic signature from at least one of said sensor assembly and said offset value and adjusting said sensor assembly in response to a change in magnetic signature;
• and
• an electronic display coupled with said electronic circuit for displaying a direction of the Earth magnetic field.

A vehicular electronic compass system, comprising:

• a magneto-responsive sensor assembly for sensing a magnetic field;
• a microcomputer system responsive to said sensor assembly for determining at least one of magnitude and direction of the Earth magnetic field, said microcomputer system collecting data points, determining from the collected data points an offset value of the Earth magnetic field and adjusting a directional heading output of said sensor assembly to account for said offset, wherein said microcomputer system occasionally calculates a new value of said offset, wherein said microcomputer system having a digital-to-analog converter converting digital values to analog signals for adjusting said sensor assembly and an analog-to-digital converter converting outputs of said sensor assembly to digital values, said analog-to-digital converter having a range of operation;
• said microcomputer system adjusting said sensor assembly and calculating a new value of said offset in response to at least one of (i) an output of said sensor assembly exceeding said range of operation of said analog-to-digital converter, (ii) an abnormal relation between collected data points and the value of said offset, and (iii) a change in value of said offset which exceeds a predetermined amount;
• and
• an electronic display coupled with said microcomputer system for displaying a direction of the Earth magnetic field.

A calibration method for calibrating a compass for use on a vehicle, said method comprising:

• sampling at least one data point of a magnetic field with a magnetic sensor;
• determining coordinates for said at least one data point relative to an origin of a coordinate system associated with the vehicle;
• estimating an origin of an Earth magnetic field from an estimated value of the Earth magnetic field magnitude and at least one data point;
• and
• adjusting the sensor to offset the estimated origin to the coordinate system associated with the vehicles.

A calibration method for calibrating a compass system for use on a vehicle, said method comprising:

• sampling at least one pair of data points that are substantially oppositely positioned relative to an axis of a coordinate system;
• averaging the substantially opposite values of said pair of data points to determine deviation from a zero value of the coordinate system;
• and
• adjusting an output of the compass system as a function of said deviation.