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Apparatus for displaying travel path

  • US 4,887,081 A
  • Filed: 12/09/1987
  • Issued: 12/12/1989
  • Est. Priority Date: 12/15/1986
  • Status: Expired due to Fees
First Claim
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1. An apparatus for displaying a travel path, direction, and current location of a running body on a X-Y coordinate map with a north direction corresponding to the Y-direction of the X-Y coordinates in which the current location is successively computed from the respective outputs of a distance detector and of a direction detector comprising:

  • the direction detector including a geomagnetism sensor and a rate-type sensor;

    the rate-type sensor detecting angular velocity;

    means for finding and storing a difference in angle between a direction detected by the rate-type sensor and a direction detected by the geomagnetism sensor at the time when a power source is turned off during travel path displaying operation; and

    means for correcting declination of the direction detected by the geomagnetism sensor by adding the stored difference in angle to the direction detected by the geomagnetism sensor at the time when the power source is turned on again, wherein when the power source is turned on said geomagnetism sensor corrected for declination of the detected direction is used exclusively to detect vehicle direction for a predetermined time sufficient for said rate-type sensor to achieve stability in performance, wherein once said stability in performance is achieved, signal processing means causes change over from the geomagnetism sensor to said rate-type sensor for exclusively detecting vehicle direction.

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