Study on rectification algorithm of irregular electronic components in surface mounter

Traditional surface mounter uses the least square method to calculate the deflection angle of electronic components by fitting a straight line according to the center of a single row of pins on the electronic component. This method can only apply to electronic components with regular pin arrangement, such as SOP (Small Out-Line Package). While the pin distribution of electronic components is irregular, it can’t calculate the deflection angle and center coordinate offset of electronic components. In this paper, an algorithm of rectifying irregular electronic components based on the minimum bounding rectangle fitting is presented. First, basing on the Canny algorithm to get the edge of the irregular electronic components, then the convex hull is constructed on the edge of the components. And finally, the deflection angle and center offset of the irregular electronic components are calculated with the minimum bounding rectangle that fitted by the convex hull of the edge. This method can be applied not only to irregular electronic components, but also to regular electronic components. The experimental results show that the detection precision of the deflection angle can reach 0.1°, the detection error of the center offset can reach 28 μm, and the average processing time of irregular component is 38 ms, which can meet the requirements of the mounter vision system for the high speed and accuracy.