Abstract: To solve the problems of large error,low efficiency and poor stability in the existing detection methods of roundness error of shaft workpieces,a sub-pixel detection and evaluation method of roundness error of shaft workpieces is proposed based on machine vision technology. This method uses polynomial interpolation-segmented curve fitting algorithm to accurately locate the sub-pixel edge of image contour.Based on obtaining the sub-pixel coordinates of image edge points,the least square method is used to detect the center coordinates,and then the roundness error of shaft workpieces is detected and evaluated. The experimental results show that the average absolute error between the measured value of this method and the measured value of the coordinate measuring machine is 8.75 μm,and the roundness error measured by this method is more uniform,the fluctuation is the smallest,and the detection accuracy is higher. It provides a feasible way for the evaluation of the roundness error of shaft workpieces.

Key words: shaft workpiece, roundness error, machine vision, sub-pixel