A three-degree-of-freedom piezoelectric-driven micro-gripper with posture adjustment

This study presents a novel three-degree-of-freedom piezoelectric-driven micro-gripper with an integrated amplifying mechanism, designed to guarantee high precision, size compactness, and controllability. Unlike conventional micro-grippers, the proposed design enables simultaneous attitude adjustment during the clamping process in all three directions of x, y, and z, significantly enhancing its dexterity and functionality. The clamped object is secured in the x-direction, rotated in the y-direction, and translated linearly in the z-direction. To evaluate the design's performance, the matrix-based compliance modeling analysis is implemented to calculate the output deformation in the x-direction, yielding a displacement of 141.39 μm. In addition, the finite element analysis is employed to calculate the holding range and validate the structural strength of the proposed micro-gripper mechanism in all three directions of x, y, and z. Subsequently, the experimental investigations are conducted to comprehensively evaluate the output performance and stiffness of the micro-gripper under varying driving voltage and frequency. The results demonstrate that the two-stage lever amplifying mechanism achieves an amplification ratio of 8.7 times in the x-direction, producing an output displacement of 87.66 μm with a bandwidth frequency of 219 Hz. In the y-direction, the gripper attains a maximum rotation speed of 508.85 μm/s under an input frequency of 350 Hz, with a resolution of 70 V. In the z-direction, the maximum moving speed is 30.87 μm/s under an input frequency of 110 Hz, with a resolution of 67.5 V. The experimental results validate the feasibility of the proposed high-precision, three-degree-of-freedom micro-gripper and demonstrate its potential for advanced micromanipulation applications, such as micro-assembly, biomedical handling, and precision manufacturing.