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Navigation system and method using map data

  • US 5,311,173 A
  • Filed: 08/28/1991
  • Issued: 05/10/1994
  • Est. Priority Date: 09/16/1988
  • Status: Expired due to Term
First Claim
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1. A navigation method using map data in a system which has at least one of first detection means for detecting a running distance of a vehicle and a second detection means for detecting an azimuth of the vehicle, a first memory for storing the map data, a data processor, and a second memory, comprising the steps of:

  • continuously detecting data, at periodic intervals, of at least one of the running distance and the azimuth by the corresponding detection means;

    deciding a quantization unit in any area in said map, corresponding to a current position of the vehicle calculated on the basis of the data detected in said detecting step, wherein said map includes roads and off-road locations, and quantization units each having a conditional probability of location of the vehicle;

    calculating a probability density of the decided quantization unit, for each quantization unit decided in said deciding step, using said data processor on the basis of the corresponding map data and the detected data which has been obtained by said detecting step; and

    correcting said current position corresponding to the decided quantization unit, based upon the calculated probability density, for each calculated probability density of the calculating step.

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