Center location of circle target captured by CCD camera

In the automated docking system for large-scale equipments, CCD camera is needed to get the circle target image of one equipment, then find the coordinates of the center of the image using for alignment of the two equipments. In order to meet real-time measurement and high-precision positioning requirements, the paper presents a CCD camera image center positioning method. Firstly, the image uses median filtering method for image enhancement, secondly, single-pixel-wide image edge of the image is fully extracted by generalized morphological structure of anti-noise in the multioperator expansion and corrosion, then a polynomial interpolation method is used for sub-pixel positioning of image edge, and finally use a radius of constrained least squares circle to fit the target image center of the circle for precise positioning. The experimental results show that it is fast, accurate, stable, its sub-pixel positioning accuracy is better than 1/20 pixel, and total standard deviation of center point is smaller than 0.01, which meets the automated docking system requirements.