Design and test of a three-stage amplifying flexible piezoelectric microgripper

WANG Haitao; CHEN Guoqiang; WANG Geng

doi:10.16186/j.cnki.1673-9787.2023060020

Abstract：Objectives In order to develop a high performance piezoelectric microgripper with large stroke,high natural frequency and precise control of force/displacement,Methods a novel design and development scheme of piezoelectric microgripper was proposed based on the principle of three-stage compliant amplifica-tion.Firstly,the calculation method of the displacement magnification of the three-stage compliant mecha-nism and the theoretical results of its static and dynamic characteristics were analyzed.Secondly,the static and dynamic characteristics were tested by finite element simulation.Then,on the basis of calibration of the prototype experimental device of the microgripper,the magnification ratio and resonant frequency were tested,and the open/closed loop accurate tracking experiments were carried out on the clamping force and the displacement of the clamp finger.Results Finally,based on the open-loop tracking experiment,the ac-tual magnification of the micro clamp is 18.41.The maximum output displacement of the microgripper is 112.3 μm and the maximum holding force is 130.1 mN when the frequency of sinusoidal voltage is 0.1 Hz and the amplitude is 100 V.Based on the closed-loop tracking experiment,it can be seen that the dynamic performance of the microgripper is excellent.The root mean square error of the finger displacement of the microgripper is 0.61 μm,and the root mean square error of the clamping force tracking is 0.88 mN.Con-clusions The above results show that the designed microgripper not only has high stroke magnification abil-ity and high natural frequency,but also can track the finger displacement and clamping force effectively.Compared with open-loop tracking,the designed microgripper can effectively suppress the nonlinear charac-teristics of low frequency operation of the system under the closed-loop tracking condition,and significantly reduce the tracking errors of force and displacement.However,advanced control method suitable for high-frequency tracking is the direction that needs to be continued research in the future.