The positioning system using the digital mark pattern-the method of measurement of a horizontal distance

We propose a self-positioning system of an autonomous mobile robot using a digital mark pattern and a CCD camera. The mark pattern is put on the ceiling as a landmark. Grey codes are written around this mark pattern. The CCD camera is put on the mobile robot to read codes on the mark pattern. In this system, the horizontal distance from the ceiling mark pattern is measured using the tilt angle of the CCD camera. The problem is a leaning camera platform. To improve this problem, we propose a method of measurement of the horizontal distance using the mark pattern image which is captured by CCD camera. The length and the width ratio of the mark pattern image depend on horizontal distance. Thus, the horizontal distance can be calculated by using the ratio between the length and the width of the mark pattern image