A Method for PCB Localization Based on Improved Cramer-Rao Lower Bound Algorithm

The precise positioning for the round mark point with high-speed and high-precision SMD was studied in this study. The standard circle, 3/4 circle, semicircle and several partial missing circle were fitted. In addition, a lot of noise and interference information were added in mark image to prove the strong robustness of this algorithm. Through the analysis of the fitting precisions of multiple information missing circles, it can be proved that the proposed algorithm has high fitting precision. Compared with the LSF algorithm and AF algorithm, this algorithm has higher precision in a low SNR circumstance. The algorithm detection speed is 2.6 times that of hough algorithm and 1.3 times that of the square method. The research results show that the precise and fast positioning of mark points in high-speed and high-precision surface mounting production can be achieved by using this algorithm.