| 摘要 |
PROBLEM TO BE SOLVED: To shorten the search process time and improve the search quality, by calculating both of a route in the forward direction from the present position to a destination and a route in the opposite direction from the destination to the present position, and determining a recommended route. SOLUTION: The data structure of a CPU searching and calculating routes is in four levels from a level 0 corresponding to a map M0 of the largest reduced scale to a level 3 corresponding to a map M3 of a magnified reduced scale on the same map area depending on how much data are detailed. A route search is controlled to be started from the level 0 and sequentially switched to an upper level. The route search is carried out both from a destination O and from a present position P1 in a forward direction and an opposite direction on the map of the level 0. As a result, for example, routes S1-S5 each connecting at a point E of the level 3 are obtained between the present position P1 and destination O. The route of the lowest cost among the obtained routes is determined as a recommended route and displayed in an overlapped state on the map to guide the vehicle. |
