A self-centering electrostatic microgripper

Abstract

Automated microassembly of micro hybrid devices is one fundamental step to reduce their high cost. Often, microassembly deals with fragile and wear-sensitive microparts that must be accurately grasped, positioned, and released or fastened in stable positions. The requirements of reliable, flexible, and fast assembly devices are other important characteristics to be achieved. This paper deals with the design of an electrostatic gripper that can grasp standard microcomponents and delicate mini and micro parts alike. The aim of this work is to theoretically and experimentally demonstrate the good performance of a self-centering gripper based on electrostatic forces. This paper extends previous works concerning electrostatic handling by adding new theoretical and FEM models, further tests, and new interpretations of the gripper’s grasping and centering capabilities. The design of the gripper is justified and supported by theoretical considerations. To better evaluate the generated force and the influences of the component on the gripper performance, FEM models are presented. Experiments concerning both grasping and releasing of mini and micro parts of different material shapes (spheres, cylinders, etc.) and dimensions (between 0.3 and 1 mm) have been performed, and quantitative measurements are reported. For industrial applications, the reliability of the grasping phase is close to 100%, the centering capability in grasping is appealing, and even if some centering errors remain, the transparency of the gripper allows the use of an eye-on-hand camera that could eliminate them during the releasing phase.