Alnico sheet measurement based on machine vision

A vision system for alnico sheet measurement is proposed in this paper, which is composed of a CMOS camera, a lens, a polygonous illuminator and a linear laser projector. The thickness of the alnico sheet is measured by laser triangulation. After the camera is calibrated and the distortion of the image is revised, edge detection and contour fitting are taken to measure the length and width of the alnico sheet. The experiment results show that measuring reproducibilities of the thickness, length and width are 0.00885mm, 0.0022mm and 0.0045mm respectively, and the uncertainty analysis shows that the calibration of the system has the biggest impact on the uncertainty.