Vision-Guided Precision Assembly

This project explores vision-guided precision assembly. Many complicated electronic products are becoming more and more capable with increased levels of functionality, while at the same time they require the integration of greater numbers of heterogeneous components in ever more compact and light-weight arrangements. Lead counts on packages are increasing while lead spacings are decreasing, placing ever greater burdens on the assembly equipment which must be able to position and place package leads to a small percentage of the lead pitch while guaranteeing the avoidance of opens and shorts. Rather than use more expensive high-accuracy motion equipment, we are using a more flexible coarse-fine approach: an ordinary industrial robot used for coarse positioning carries with it a precision mini-robot for fine positioning. The coarse robot accesses a large workspace needed for component parts feeders but is not sufficiently accurate by itself to align and place the components during the assembly. The fine-motion mini-robot, however, is one-hundred to a thousand times more precise than the coarse robot carrying it, and is capable of rapid motion at the sub-micrometer level. The mini-robot carries pickup and placement tooling for the components and a high-resolution camera connected to a vision system. The mini-robot is directly controlled by visual alignment information, independently of the coarse robot motion.