| 摘要 |
PURPOSE: To seek a vehicle position in a highly accurate manner by finding a distance error quantity to the actually-to-be-value of output in a travel distance calculating means on the basis of the direction information, travel distance of a vehicle and the road data of a road map, and correcting a distance coefficient in a direction where this distance error quantity is decreased. CONSTITUTION: With an absolute direction calculated by an output value of azimuthal sensor 202 and a direction variation to be outputted from an angular velocity sensor 201, a vehicle's estimated direction is determined. A pulse number being outputted by a car speed sensor 203 is counted by a counter 216, and a distance coefficient is multiplied to the counted value, thereby seeking a traveling distance. Since this traveling distance per rotation of a tire is varied by an abrasion loss or the like in the tire, a distance between a new road inn time of completion of both right-left turns is found out as a distance error quantity the distance coefficient is renewed in a direction where it is decreased or increased by those of overshoot/undershoot of a measured current position to be produced due to a too-much or too-little extent of the distance coefficient according to this distance error quantity. |
