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Location detection system by an on-board slit camera imaging road surface marks and its application

In this paper we propose a precision localization system with an on-board camera and specific road surface marks. An on-board camera is mounted downward and marks for position detection are put on road surface. The mark is detected by image processing of the resulting road surface image. The detected mark gives the vehicle position in each lane. Position related information can be attached by some simple coding schemes. The vehicle direction corresponds to inclination of the mark in the image and vehicle speed is given by the time difference of mark detection between frames in the case of a 2D video camera. We use a slit camera instead of a 2D video camera. Advantages of using the slit camera are high longitudinal resolution and simplified image processing for mark detection. The longitudinal length of mark in the slit image gives the speed information. By mounting two slit cameras at the front and rear end of the vehicle, a precise speed can be measured by the time difference of mark detection. A cross mark consisting of four separate bars is selected as a road surface mark for position detection. The position is given in subpixel accuracy as a crossing point of two straight lines. Experiments with a passenger vehicle show the effectiveness of this system.