Design of a large-stroke compliant gripper with position and force sensing for precision grasping

Precise grasping using compliant grippers is a crucial step in many micro/nano manipulations, which require grippers to exhibit excellent static and dynamic performances. This paper presents a novel piezoelectric-driven compliant gripper with position and force sensing. A series structure that combines a differential amplification mechanism with a Scott-Russell mechanism is introduced to enhance the grasping stroke (GS). To ensure linear motion of the jaws, a series-parallel hybrid parallelogram mechanism is employed. Analytical models for the motion amplification ratio, input stiffness, and natural frequency of the proposed gripper are developed based on the pseudo-rigid body model. Structural optimization is conducted using the response surface method to determine the geometrical parameters of the gripper. Finite element simulations are performed to assess both static and dynamic performance. A prototype of the gripper has been fabricated for open-loop and closed-loop performance tests. Experimental results demonstrate that the gripper exhibits a large GS, high positioning and grasping accuracy, and high natural frequency, which indicates its significant potential for applications in micro/nano manipulations.