| 摘要 |
PROBLEM TO BE SOLVED: To provide a route retrieving method for use with an on board navigation system, whereby the vehicle can arrive at the destination by the desired time of arrival while saving as much of the toll as possible. SOLUTION: Once a destination and the desired time of arrival has been set via a control part 2, a control part 15 retrieves a candidate for a route that allows the vehicle to take the shortest time to arrive at the destination, and calculates the estimated time of arrival when the vehicle travels along the candidate for the route. If the estimated time of arrival is earlier than the desired time of arrival by a predetermined time or more, another candidate for a route whereby the vehicle does not need to pass a section of a toll road involved in the former candidate for the route is newly retrieved, and the estimated time of arrival when the vehicle travels along the latter candidate for the route is calculated. Thus sections not including a toll road are increased, and the route is retrieved as the estimated time of arrival is compared with the desired time of arrival. |
