Vehicle navigation system

Claim 1

A vehicle navigation system comprising: (a) means for detecting traveling conditions of a vehicle; (b) means for calculating a present position of the vehicle on the basis of the detected vehicle traveling conditions; (c) means for holding data representing preset reference points located at intersections and at unforked straight roads, data representing whether the respective preset reference points are located at the intersections or at the unforked straight roads, and data representing distances between the adjacent preset reference points; (d) means for determining a target reference point toward which a vehicle is traveling, the target reference point being selected from the preset reference points; (e) means for determining whether or not the target reference point is located at an intersection or at an unforked straight road; (f) means for, in cases where the target reference point is located at an intersection, detecting curvature of motion of the vehicle while the calculated vehicle position remains in a check range around the target reference point; (g) means for, in cases where the target reference point is located at the intersection, forcedly setting the calculated vehicle position, at which the detected curvature of motion of the vehicle is maximized, to the target reference point; (h) means for detecting a distance traveled by the vehicle from a preceding reference point which the vehicle passed last; and (i) means for, in cases where the target reference point is located at an unforked straight road, forcedly setting the calculated vehicle position, at which the vehicle traveled distance equals a distance between the target reference point and the preceding reference point, to the target reference point while the calculated vehicle position remains in said check range around the target reference point.