| 摘要 |
PCT No. PCT/JP88/01305 Sec. 371 Date Aug. 23, 1989 Sec. 102(e) Date Aug. 23, 1989 PCT Filed Dec. 23, 1988 PCT Pub. No. WO89/06345 PCT Pub. Date Jul. 13, 1989.A navigation apparatus for a vehicle includes a vehicle speed sensor (1-a) for detecting an actual vehicle speed, an odometer (1-b) for detecting a travel distance of the vehicle, a processing unit (5) for calculating a present position from the detection signals from the vehicle speed sensor and the odometer, and a display means for displaying the calculated present position on a map displayed. The actual vehicle speed is compared with an angular velocity of the wheel obtained by the odometer (1-b), and, only when the difference between the actual vehicle speed and the angular velocity of the wheel exceeds a predetermined value, the travel distance is calculated using the actual vehicle speed. The actual vehicle speed sensor (1-a) may include two photosensors. The vehicle speed is operated using the degree of coincidence of the two waveforms. Furthermore, the travel distance is calculated after the vehicle has travelled a fixed distance or for a fixed period of time.
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