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Method of correcting magnetization vector

  • US 5,349,529 A
  • Filed: 06/22/1992
  • Issued: 09/20/1994
  • Est. Priority Date: 06/25/1991
  • Status: Expired due to Fees
First Claim
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1. A method of correcting the output of a magnetization vector detector of a stand alone navigation system of a mobile body, said mobile body having said magnetization vector detector and a geomagnetic vector detector, said method comprising:

  • detecting a magnetization vector Mn-1 with said magnetization vector detector, said magnetization vector being directed from a reference position toward the center of a magnetic circle which indicates the magnetized condition of the mobile body;

    determining the direction of progression of the mobile body and detecting a geomagnetic vector Sn which is directed from the reference position in the direction in which the mobile body progresses;

    calculating an instantaneous direction vector Rn which is directed from the center of the magnetic circle in the direction in which the mobile body progresses and which has a direction angle Θ

    mn according to the equation Rn =Sn -Mn-1 ;

    calculating an average geomagnetic intensity ron from the average of past values of the magnitude rn of the instantaneous direction vector Rn, and a weighing coefficient hn that is a positive real number no greater than 1 based on the average geomagnetic intensity ron ;

    calculating a substantially instantaneous magnetization vector Hn for correcting the magnetization vector Mn-1 according to the equation;

    Hn =Sn -ron ·

    exp(jΘ

    mn);

    determining the corrected magnetization vector Mn from the magnetization vector Mn-1, the weighing coefficient hn, and the substantially instantaneous magnetization vector Hn according to the equation;

    Mn =(1-hn

    Mn-1 +hn ·

    Hn andcorrecting an output of said magnetization vector detector in accordance with said determined corrected magnetization vector.

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