Development of a Highly Compact Microgripper Capable of Online Calibration for Multisized Microobject Manipulation

In this study, we developed a highly compact microgripper with an only 300-μm thick jaw and yet an amplification ratio of more than 20. A total of 18 flexure hinges were employed to achieve a low impedance grasping mechanism and diminish backlash. To achieve precise manipulation, a strain-gage-based position sensor was embedded within the microgripper to investigate the jaw displacement. Conventionally, the position sensors were calibrated by additional equipment, such as laser sensor to adjust the jaw motion stroke for the manipulation of multisized objects, which was a sophisticated process. To avoid such process, we proposed a simple visual-based online calibration method. As a result, the effectiveness and feasibility of the proposed method were verified successfully in picking and placing microspheres and microobjects with the scale ranging from hundreds of microns to a few.