Visual alignment robot system: Kinematics, pattern recognition, and control

The visual alignment robot system for display and semiconductor fabrication process largely consists of multiaxes precision stage and vision peripherals. One of the central issues in a display or semiconductor mass production line is how to reduce the overall tact time by making a progress in the alignment technology between the mask and panel. In this paper, we suggest the kinematics of the 4PPR parallel alignment mechanism with four limbs unlike usual three limb cases and an effective pattern recognition algorithm for alignment mark recognition. The inverse kinematic solution determines the moving distances of joint actuators for an identified mask-panel misalignment. Also, the proposed alignment mark detection method enables considerable reduction in computation time compared with well-known pattern matching algorithms.