Compensation system for electronic compass

  • US 5,644,851 A
  • Filed: 10/25/1993
  • Issued: 07/08/1997
  • Est. Priority Date: 12/20/1991
  • Status: Expired due to Term
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First Claim
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1. A method for compensating for the effect of a deviating magnetic field in a vehicle compass, said compass comprising:

  • first and second magnetoresistive sensors responsive to an external magnetic field for developing electronic signals representative of said external magnetic field, said external magnetic field being a combination of the earth magnetic field and a deviating field of the vehicle,said first and second sensors being oriented in a predetermined angular relation with each other, and being aligned in a predetermined angular relation with respective axes of said vehicle,each of said sensors including means for nullifying at least part of a deviating magnetic field which impinges on it, said method comprising the steps of;

    determining whether the value of the sensor signal of each sensor is different from a nominal value which corresponds approximately to the value of the earth magnetic field,if it is, using said nullifying means for adjusting the magnetic field impinging on each sensor to adjust the sensor signal to a value approximately equal to the nominal value,determining the maximum and minimum peak values of each sensor signal,determining the average of said peak values of each sensor signal,and mathematically compensating the actual value of each sensor signal in accordance with the respective average value.

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