| 摘要 |
PROBLEM TO BE SOLVED: To provide a car navigation system which can more precisely detect the position of own vehicle, when traveling on a road which is parallel to and in the vertical directions to a high-level road. SOLUTION: In the car navigation system having a GPS device 1 for receiving radio waves from a plurality of GPS satellites and for calculating the current position of own vehicle and a road data part 5, a current position calculating part 31 includes a map matching part 31a, an up and down determining part 31b, a Y-junction detecting part 31c, and a Y-junction deciding part 31d. The GPS device includes a reception condition monitoring part 11 for monitoring the reception conditions of the satellite radio wave, and outputs information on the reception condition to the current position calculating part. The Y-junction detection part detects a Y-junction of the roads from the road map data, on the basis of the current position. When the vehicle is traveling on the detected Y-junction of the roads, the Y-junction deciding part decides whether own vehicle is traveling on either of the sides of the junction of the roads, at the Y-junction of the roads, on the basis of the variation in the reception sensitivity of the radio waves received from the GPS satellite in the left side or the right side in the sky, with respect to the traveling direction. COPYRIGHT: (C)2005,JPO&NCIPI |
