Design of a 2-DOF Constant Force Compliant Microgripper for Optical Switch Assembly

In consideration of the requirements of the polarization alignment in optical switch assembly and the overloading protection for the optical fiber in contact, a novel 2-DOF constant force microgripper is developed with the functional modules of grasping and rotating under overloading protection. Based on the negative stiffness effect, the coantant force mechanisms take more advantages in microassembly than traditional grippers with integrated force sensors in terms of the simplification of control algorithms and the miniaturization of overall size. To avoid the surface damage by the overloaded grasping and the rubbing operation, a parallel constant force microgripper with a grasping module and a rotating module is designed to avoid sliding friction of optical fiber during assembly. Then, the analytical models are constructed to derive the static and kinematic performances. Finally, the analytical results are validated. It is observed that i) the grasping force is approximately constant at 544.69 mN in a range between 835 mu m and 1336 mu m; ii) the constant force rotating stroke reaches 6.70 degrees.