Design and control of a large-stroke piezoelectric micro-gripper based on flexible crank-slider mechanism

Piezoelectric ceramic actuator (PEA)-driven micro-grippers represent a key technology for micro-manipulation and micro-assembly processes at micro/nano scales. To address the limited stroke of PEAs, this paper proposes a design and analysis method for a large-stroke micro-gripper based on a flexible crank-slider mechanism, along with experimental validation. Kinematic equations were established to investigate the relationship between the displacement amplification ratio and the dimensions/positions of crank-slider linkages, deriving geometric conditions for achieving high amplification ratios. The influence of flexure hinge posture on transmission efficiency was analyzed, and a compact micro-gripper structure was designed using straight-beam flexure hinges. Finite element simulations were employed to analyze the micro-gripper’s amplification ratio, input stiffness, and modal characteristics. Experimental studies on nonlinear compensation for PEAs were conducted, evaluating the micro-gripper’s stroke, amplification ratio, and resolution. Simulation and experimental results demonstrate close alignment between measured parameters and theoretical values. The proposed flexible crank-slider-based micro-gripper features a simple, compact structure, achieves an amplification ratio of 32 times, and delivers a stroke of 640 μm.