Design and development of a 3-DOF compliant gripper with in-plane and out-of-plane motion

Abstract

This paper presents a novel piezoelectric-driven, three-axis compliant gripper with in-plane and out-of-plane motion for grasping and rubbing tiny rigid objects. The gripper features in-plane motion actuated by two piezoelectric actuators and out-of-plane motion enabled by a piezoelectric sheet. The displacement amplification ratio of the in-plane motion is derived using elastic beam theory, and static analysis is performed using the pseudo-rigid body model (PRBM). An out-of-plane bending displacement model of a piezoelectric cantilever beam is established based on piezoelectric theory. Finite element simulations and experimental tests validate the theoretical models. The gripper achieves a gripping stroke of 914.3 μm, an in-plane rubbing stroke of 317.2 μm, and an out-of-plane rubbing stroke of 165.8 μm. The gripper successfully grasps and rubs metal wires (diameters of 200 μm–800 μm) and a small steel ball with a diameter of 500 μm, demonstrating excellent spatial manipulation for small cylindrical and spherical objects.