摘要 |
According to the present invention, a laser sensor detects a vehicle and a beacon notifies an onboard unit via wireless communication about the time of detection at which the laser sensor detected the vehicle and a correction reference position for correction as a position at which the vehicle existed at the detection time. The onboard unit calculates a position at which the vehicle exists at each point in time on the basis of the distance travelled by the vehicle, and corrects the calculated position on the basis of the detection time received from the beacon and the correction reference position. |