| 摘要 |
PURPOSE:To avoid mistakes in matching with a map when a vehicle travels on roads which branch from each other at a relatively small angle. CONSTITUTION:Each time a vehicle travels over a fixed distance, a vehicle position/bearing calculating portion 5c calculates the amount of change of the vehicle position and adds the amount to the previous determined vehicle position to find an estimated vehicle position. For the estimated vehicle position, a vehicle position modifying portion 5d refers to data about roads read from a CD-ROM 1 and searches for links usable in matching based on projection method in order of precedence. When there is one link found to be usable in matching, the estimated vehicle position is projected to the link and regarded as the current determined vehicle position. When there are a plurality of usable links found and when at least the usable link which is the highest in the order of precedence and that which is the second highest in the order of precedence branch from the same node at below a predetermined small angle, the estimated vehicle position is directly used as the current determined vehicle position. Otherwise the estimated vehicle position is projected to the usable link which is the highest in the order of precedence is regarded as the current determined vehicle position. |
