Design and Development of a New Piezoelectric-Actuated Biaxial Compliant Microgripper With Long Strokes

In this paper, a new piezoelectric-actuated biaxial compliant microgripper with long strokes is proposed for automatically gripping and rolling tiny rigid objects. In order to improve the working stroke and maintain a compact footprint, a counter-side distributed two-stage lever amplifier with parallelogram mechanism is introduced. Based on the pseudo-rigid body model, analytical models of the displacement amplification ratio, input stiffness, and natural frequency of the left- and right-sided gripper mechanism are established. Structural optimization and performance simulation of the proposed microgripper mechanism are carried out with finite element analysis simulation. A prototype microgripper has been fabricated for open-loop and closed-loop tests to verify its working capabilities. The clamping and rubbing experiments show that the designed microgripper can grasp and rub an optical fiber with the diameter of 200
$\mu \text{m}$
for rolling over 45°. The developed microgripper has a promising application in precision micromanipulation fields such as optical fiber alignment. Note to Practitioners—This work is motivated by the requirement of designing a biaxial microgripper with both a large working stroke and compact structure for complex operation in optical fiber alignment. Through a series of open-loop and closed-loop experiments on the developed prototype, it is demonstrated that the proposed dual-axis microgripper has superior working performance. The clamping stroke and rubbing stroke of the gripper are
$251.2~\mu \text{m}$
and
$225.0~\mu \text{m}$
, respectively. The first two natural frequencies of the gripper are 350.63 Hz and 603.37 Hz, which correspond to the working modes of the right-side and left-side gripper mechanisms, respectively. The closed-loop experimental results show that the resolution of output displacement of the gripper is close to
$1.2~\mu \text{m}$
and the resolution of the clamping force is 3 mN. As compared with the reported microgrippers in previous work, the designed mechanism exhibits both a large working stroke and high resonant frequency for ensuring the reliability and rapidity of micromanipulation task.