Defect Circle Measurement Based on Twice Hough Transform

摘要

The circle center and radius of the holes parts is generally measured with Hough transform, if it has defect on the circumference, due to the impact of defective parts, there would be a big measurement error for the circle center and radius directly with Hough transform, so, defective parts must be removed before measurement. In this paper, twice Hough transform method is proposed, the improved Hough transform algorithm of circle center and radius variable separation is designed. The first Hough transform is employed to measure the circle center and radius roughly, determine whether it has defects according to the distribution of the parameter space point, and remove defective parts; the second Hough transform is used to measure the circle center and radius accurately. Experimental results show that the accuracy of hole-center distance measurement is increased by 1%, and the diameter measurement accuracy b improved by 0.5% with proposed method.