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Navigation system mounted on vehicle

  • US 5,416,477 A
  • Filed: 02/18/1993
  • Issued: 05/16/1995
  • Est. Priority Date: 11/06/1990
  • Status: Expired due to Fees
First Claim
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1. A navigation system adapted to be used with a vehicle, said navigation system comprising:

  • means for receiving an input of information of said vehicle'"'"'s movement;

    estimated location-direction calculating means, receiving said information of said vehicle'"'"'s movement, for calculating an estimated vehicle existence location by deriving a vehicle movement vector on the basis of said information of said vehicle'"'"'s movement and for adding said vehicle movement vector to an already known location and direction of travel of said vehicle;

    straight condition processing means, receiving said information of said vehicle'"'"'s movement, for judging by said information of the vehicle'"'"'s movement whether or not the vehicle is in a condition of straight travel and for forming at least one straight travel locus when said straight condition processing means judges that said vehicle is in the condition of straight travel, thereby forming an imaginary locus comprising said at least one straight travel locus;

    means for receiving an input of map data;

    road searching-straightening processing means, receiving said at least one straight travel locus, for extracting from said map data information concerning at least one road which corresponds to said at least one straight travel locus to thereby form an imaginary route comprising said at least one straight road;

    direction rectifying data calculating means, receiving said at least one straight travel locus and said imaginary route, for finding a direction offset which is a function of direction errors between said at least one straight travel locus and one of said at least one straight road corresponding to the at least one straight travel locus, and for calculating direction unconformity degree in accordance with direction differences still remaining between said at least one straight travel locus and said corresponding one of said at least one straight road after said direction offset is removed from said imaginary route;

    location rectifying data calculating means, receiving said imaginary locus and said imaginary route, for finding a location offset which is a function of location errors of a turning point of said imaginary route with respect to a turning point of said imaginary locus when an intersection of adjacent straight travel loci of said imaginary locus is defined as said turning point of the imaginary locus and an intersection of adjacent straight roads of said imaginary route after directions of said adjacent straight roads have been corrected for said direction offset is defined as said turning point of the imaginary route, and for calculating a location unconformity degree on the basis of a location difference still remaining between said turning point of the imaginary route and said turning point of said imaginary locus after said location offset is removed from said imaginary locus; and

    location-direction rectifying means for rectifying a location and direction of the vehicle by respectively applying said direction offset and said location offset to an estimated direction and an estimated location in a case of said direction unconformity degree and said location unconformity degree respectively being within predetermined threshold values.

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