Hu Luqing, Wang Hongxi, Wang Guanwei, Liang Wenhong
School of Mechatronic Engineering, Xi'an Technological University, Xi'an 710021, China.
Rev Sci Instrum. 2024 Mar 1;95(3). doi: 10.1063/5.0175361.
Piezoelectric actuators commonly used in microgrippers have a small stroke, and their accuracy is reduced by the transmission amplification unit, which leads to a contradiction between the clamping range and the clamping accuracy in existing piezoelectric-actuated microgrippers. This paper proposes a design scheme to divide the total clamping range of the microgripper into segments based on the compliant multistable mechanism (CMM). First, by using the stable equilibrium positions of the CMM, the total clamping range of the microgripper is divided into multiple smaller clamping sub-intervals to accommodate objects of different scales. Then, the theoretical models of the displacement amplification ratio of the microgripper amplification mechanism and the stiffness of the microgripper in different clamping sub-intervals are established, and the force-displacement characteristics of the CMM are analyzed. Next, through finite element simulation, the correctness of the theoretical analyses is verified, and it is shown that objects between 0 µm and 1.650 mm can be clamped using four clamping sub-intervals under a five times displacement amplification ratio. Finally, a microgripper of the CMM consisting of two three-segment fully compliant bistable mechanisms connected in series is designed and machined, and microgripper segmented clamping experiments are conducted. The experimental results demonstrate the feasibility of the design scheme proposed in this paper.
微夹钳中常用的压电致动器行程较小，且其精度会因传动放大单元而降低，这导致现有压电驱动微夹钳在夹持范围和夹持精度之间存在矛盾。本文提出一种基于柔顺多稳态机构（CMM）将微夹钳的总夹持范围进行分段的设计方案。首先，利用CMM的稳定平衡位置，将微夹钳的总夹持范围划分为多个较小的夹持子区间，以适应不同尺寸的物体。然后，建立微夹钳放大机构位移放大比和不同夹持子区间微夹钳刚度的理论模型，并分析CMM的力-位移特性。接下来，通过有限元模拟验证理论分析的正确性，结果表明在五倍位移放大比下，使用四个夹持子区间可夹持0 µm至1.650 mm之间的物体。最后，设计并加工了一个由两个串联的三段式全柔顺双稳态机构组成的CMM微夹钳，并进行了微夹钳分段夹持实验。实验结果证明了本文提出的设计方案的可行性。
