A VISION-MEASURING METHOD FOR AN IMPERFECT CIRCLE
Kuang-Chyi Lee, Chien‐Chang Lin · Journal of the Chinese Institute of Industrial Engineers · 2005
The positioning center of the circular hole of PCB and the reference coordinates of welding by optical point in the manufacture process of the semiconductor components will cause the circle deformed and will create image noise or blurred image when the image from CCD camera is grabbed by the different lighting method or light source. When the surface of objects inspected reflect the light, it will cause the error of center positioning. This paper proposes a 4-points mode number method for the center positioning to overcome the problem of the measurement of the imperfect circle. The results of simulation and experiments indicate that this method is feasible and it can measure accurately the coordinates of the center of the circle which is covered by the other objects or is deformed over sixty degrees. Based on experiments, it is known that the 4-points mode method is faster and more accurate than the area, 3-points, contour-tracking and least-squares error methods of center-positioning.