Global visual servoing of miniature mobile robot inside a micro-assembly station

This paper focuses on designing the 2D global visual servoing system of the miniature mobile robot. The global vision sensor supervises the robot's workspace to detect the position and orientation of the robot, and then navigates the robot's end-effector into view field of the microscope to accomplish MEMS (Micro Electric Mechanical System) parts assembly. To meet requirements of real-time control and high precision tracking, three LEDs forming a non-isosceles-right-angled triangle are mounted on the top of the robot platform. Visual servoing is realized with dynamic look and move mode, and the controller is designed in the image space. With the global visual navigation, the robot can be controlled with accuracy about 0.5-1 mm. But due to the lack of interior sensor for the manipulator, when the macro motion is completed, the end-effector is not guaranteed inside view field of microscope. The strategy for end-effector searching, which based on motion inspection, is designed to solve the problem. Experiment shows that the end-effector can be located in the view of microscope successfully. It is the essential precondition for our robot accomplishing micro operation task.