| 摘要 |
PROBLEM TO BE SOLVED: To obtain a navigation apparatus whose accuracy can be enhanced by a method wherein a movement distance is found on the basis of speed information to be output from a speed detection means, a movement direction is found on the basis of direction information to be output from a direction detection means, the distance and the direction are accumulated and computed and the estimated position on a vehicle is found. SOLUTION: When the previous position of a vehicle exists, a position computing device 5 reads out information on a road near the previous position from a CD-ROM device 4, and it acquires the feature of the connection of the road. When the continuation number of simple links of a running road is smaller than a prescribed value or when both ends of a link display a crossing, 'an urban-district mode' is judged. On the other hand, when the continuation number is at the prescribed number of higher, 'a suburban-part or mountain-part mode' is judged from a data on the absolute position of a vehicle is acquired from a GPS device 1, a self-sustaining speed is acquired from a vehicle speed sensor, and a direction is acquired from a direction sensor. The self-sustaining speed is corrected by using the GPS speed of the vehicle. On the basis of the continuation number of simple links in the road information, a running mode is judged. The limit value of a speed change and a retrieval range are set according to it, and a position is computed according to a running situation. |
