Computer-integrated micro-assembling with image-servo system for a microdroplet ejector

In this paper, the micro-assembling tasks of the positioning system are discussed; an automatic micro-assembling system with vision-servo system is proposed to replace manual operations for assembling a microdroplet ejector; it consists of three-axis micro-stepping positioning stage and the image recognition system, which is composed of two CCD cameras with lenses and a designed image recognition code in C++ builder. For the image recognition system, circle outlines and a cross positioning mark are used to guide the micro-stepping stage to achieve assembling tasks. In the visual-servo system design, the automatic positioning with vision guidance is separated into two steps, which are the coarse positioning task with the global vision and the fine positioning task with the micro vision. For the coarse positioning task, the Sobel operator is used to find outline of positioning mark and then to calculate centre and radius by using the way of least-mean-square error algorithm. For the fine positioning task, the Hough transform is applied to find the straight line of the cross positioning mark. Finally, the micro-stepping positioning stage and image recognition system are integrated into an automatic vision-servo micro-assembling system by a designed code to achieve micro-assembling tasks automatically.