In order to control the traveling of a vehicle correctly, it is necessary to estimate the position of the vehicle upon road map data in an accurate manner. However, since position measurement errors of around several tens of meters can be generated by the GNSS (Global Navigation Satellite System), it is difficult to estimate an accurate position for the vehicle within the road along with it is traveling, even if corrections are performed by using map data and map matching.
Accordingly, a system is per se known that controls the traveling of the vehicle by using information such as the shapes of roads (curves, intersections, and the like), the attributes of roads (speed limits, road gradients, and the like), and so on. The techniques disclosed in Patent Document #1 and Patent Document #2 are per se known as prior art techniques by which enhancement of the accuracy of estimation of the position of a subject vehicle is implemented.
In Patent Document #1, a technique is disclosed for enhancing the accuracy of estimation of the position of the vehicle by attaching a camera to the vehicle, by recognizing, from the camera images obtained during traveling, landmarks which are characteristic objects from which the position of the vehicle can be accurately known such as traffic lights, traffic signs, lines painted upon the road and so on, and by implementing appropriate corrections.
And, in Patent Document #2, a technique is disclosed for implementing management of information for a landmark for which the level of accuracy of existence is high by making a decision as to whether or not to report the result of recognition to a map center, in consideration of the likelihood of the result of landmark recognition and/or of the conditions during photography of the image.