Sub-pixel Measurement System of Circle Outer Diameter Based on Zernike Moment

Abstract

Sub-pixel measurement system can to some extent compensate the margin positioning error caused by hardware limitation. A kind of sub-pixel measurement system of circle outer diameter based on Zernike moment is established. Sub-pixel edge detection algorithm of circular workpiece based on Zernike moment is proposed and further positioning of edge points in the gradient direction by the adoption of quadratic polynomial interpolation is conducted. Finally, circle outer diameter measurements of sub-pixel accuracy are obtained by using least square method fitting the edge points. The experiment results show that the measurement accuracy of system is high, which meets the requirement of high accuracy measurement of circular workpiece.