Characterization of a compact piezoelectric actuated microgripper based on double-stair bridge-type mechanism

This paper presents a compact flexure-based microgripper for grasping/releasing tasks. The microgripper is based on a double-stair bridge-type mechanism and consists of a bridge-type mechanism for amplifying the input displacement and the integrated parallelogram mechanisms for linearizing the motion at the microgripper jaws. The displacement transmission, amplification, linearization are accomplished in a single-stage. Stiffness modeling is established to characterize the output displacement, the displacement amplification ratio, and the input stiffness of the mechanism. The right-angle flexure hinges are utilized in the displacement amplification and transmission mechanisms to maintain the input stiffness of the mechanism. The structural design of the microgripper is optimized in such a way that a large output displacement can be achieved. Finite element analysis and experiments are conducted on the microgripper to verify the results of the analytical modeling. The proposed microgripper achieves a large output displacement of 543.8 μm with a displacement amplification ratio of 19.3. The experimental results indicate that the microgripper will be able to accommodate a grasping/releasing task.