<title>Vision-based orientation and position detection of ICs and PCBs</title>

Abstract

In this paper, a high-resolution algorithm for detecting the orientation and position of an IC, and an algorithm for compensating the position and skew angle of a PCB, are proposed. The proposed algorithm for the first topic consists of two parts. Its first part is a preprocessing step, in which corner points of an IC are detected and are separated into two groups. Then the coarse angle of the principal axis is obtained by line fitting. The second part is a main processing step, in which the Hough transform over the limited range of angles is applied to the corner points to detect precisely the orientation of an IC or a surface mounting device (SMD). The position of an IC or SMD is determined by using its four corner points. The proposed algorithm for the second topic is the one which detects a rotation angle and translation parameters of a PCB using a template matching method. The PCB is compensated by the detected parameters. The computer simulation shows that the parameters obtained by proposed algorithms are more accurate than those by the several conventional methods considered. The proposed algorithms can be applied to the fast and accurate automatic inspection systems.