Application of visual servo-control X–Y table in color filter cross mark alignment

A low-cost PC-based control X–Y table is constructed with AC servo motors and ball screw mechanisms to achieve long-range micro-positioning. This X–Y mechatronics system is integrated with a machine vision system to construct a visual based motion control system for industrial positioning applications, especially for the optical inspection purpose. Although the visual based servo system has the vision information to guide the servomechanism motion, it cannot obtain accurate positioning objective, especially, for the micro–nano positioning. It still needs a good servo controller to monitor the object step change after receiving the motion command from the machine vision system. Here, a new intelligent model-free controller was proposed to achieve quick transient response and precise steady state accuracy. The integration of this intelligent servo system and a machine vision system is implemented on the LCD color filter cross mark alignment application. The dynamic positioning performance and robustness of this control system are evaluated based on experimental results.