A Piezo-based Microgripper with Hybrid Grasping Modes for Versatile Micro-object Handling Tasks

This paper introduces a new monolithic piezo-driven microgripper which can perform both parallel and angular grasping techniques in both symmetric and asymmetric modes. Four bridge-type mechanisms with two lever-type side arms construct the whole geometry of the microgripper. Basically, the simultaneous actuation of the bridge-type mechanisms will activate symmetric/asymmetric parallel grasping modes. Conversely, the lever-type side arms along with the bridge-type mechanisms will assist in symmetric/asymmetric angular grasping. In general, it has been experienced that each type of grasping technique has its individual limitations. So, enriching the ability to perform multiple grasping operations from the same geometric configuration of the microgripper can be a good solution in terms of enhancing versatility. Further, to evaluate the performance of the microgripper during different grasping modes, Finite Element Analysis has been conducted. From the computational study, the microgripper can achieve an overall displacement amplification ratio of 4.52 and 18.62 during parallel and angular grasping mode respectively. Moreover, the maximum equivalent stress during different grasping modes has been evaluated which illustrates a minimum safety factor of 1.66 in the worst case. Finally, the dynamic performance evaluation via Modal analysis ensures a natural frequency of 321.96 Hz in the first mode shape of the microgripper. Thus, the microgripper will perform parallel/angular grasping in symmetric/asymmetric mode effectively.