Design of a Microgripping System with Visual and Force Feedback for MEMS Applications

This paper reports the design of a microgripping system with visual and force feedback for handling and assembly in microtechnology. The system consists of a microgripper, an electromagnetic microactuator, the Kleindiek micromanipulator MM3A, a light microscope, a CCD camera and a computer. The microgripper is mounted on the Kleindiek micromanipulator MM3A which has 3 degrees of freedom (two rotational axes, one linear axis), wide working range (240deg in the rotational axes, 12 mm in the linear axis) and subnanometer resolution. An external CCD camera provides images for obtaining the actual axis positions and by applying inverse kinematics the actual position of the manipulators end-effector is calculated so as to perform coarse positioning. A second CCD camera in combination with a light microscope provides sufficiently precise data to perform the actual manipulation tasks. Since the gripper is electromagnetically driven, the movement of the gripper tips is a continuous mapping of the applied current. The applied current can be correlated to the actual distance between the tips by calibration. In case of gripping an object, the tips are hindered to close to the full extent. The resulting gripping force depends on the actual distance changes.