Design and Modeling of a Piezoelectric-Actuated Microgripper Based on Reversed Scott Russell and Differential Lever Amplification Mechanisms

To address the limited grasping stroke (GS) of piezoelectric-actuated microgrippers, this paper proposes a novel symmetric microgripper configuration integrating reversed Scott Russell (S–R) mechanisms and differential lever amplification mechanisms (DLAMs). Four reversed S–R mechanisms are arranged in parallel and connected via a central linkage, which is actuated by a piezoelectric stack actuator (PSA). The tension–compression deformation of the parallel S–R units generates two pairs of displacements with equal magnitudes and opposite directions, which are further transmitted to the DLAM to amplify the GS. A semi-analytical mechanical model of the microgripper is established, incorporating a simplified PSA model to describe the mechanical behavior of the actuator. Based on the analytical model, the displacement amplification ratio (DAR) and first-order natural frequency (FNF) are selected as dual optimization objectives to optimize the structural geometric parameters. The static and dynamic performances of the proposed microgripper are preliminarily validated via finite element simulations and experiments. Experimental results show that the microgripper achieves a GS of 857 μm, a bilateral DAR of 68, and an FNF of 265 Hz. Although the modeling error is relatively large, the established model can still provide guidance for the integrated design of the microgripper. Finally, grasping tests further demonstrate that the developed microgripper can be applied to micromanipulation and microassembly tasks.