Vehicle compass compensation

  • US 6,922,902 B2
  • Filed: 01/28/2003
  • Issued: 08/02/2005
  • Est. Priority Date: 04/08/1999
  • Status: Expired due to Fees
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First Claim
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1. A vehicular electronic compass system comprising:

  • a magneto-responsive sensor assembly for sensing a magnetic field, said magneto-responsive sensor comprising at least a two-axis sensor for sensing two components of a magnetic field, said two-axis sensor comprising a first axis sensing element and a second axis sensing element, one of said first axis sensing element and said second axis sensing element being generally aligned with a direction of travel of a vehicle when the vehicular electronic compass system is operated in the vehicle;

    an electronic circuit responsive to said two-axis sensor for distinguishing the Earth magnetic field from a deviating field of the vehicle in order to determine a directional heading of the vehicle;

    said electronic circuit including a microprocessor and an analog-to-digital converter;

    said distinguishing the Earth magnetic field from a deviating field of the vehicle incluiding an initial calibration mode that brings the output signal of at least one of said first axis and second axis sensing elements to be within the operable range of said analog-to-digital converter and wherein said electronic circuit detects a first peak value of the Earth magnetic field by said microprocessor of data sensed by one of said first axis and second axis sensing elements, wherein said electronic circuit detects a second peak value of the Earth magnetic field by processing by said microprocessor of data sensed by said one of said first axis and second axis sensing elements, wherein said electronic circuit calculates a zero reference value using said detected first and second peak values, wherein said electronic circuit detects a third peak value of the Earth magnetic field by processing by said microprocessor of data sensed by the other one of said first axis and second axis sensing elements, and wherein said electronic circuit algorithmically calculates a fourth peak value of the Earth magnetic field using said detected first, second and third peak values without a need for the vehicle to turn through a 360 degree circle; and

    an electronic display coupled with said electronic circuit, said electronic display displaying the directional heading of the vehicle at least during said initial calibration mode.

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