The Mechanism And Experimental Research On Piezoelectric Stick-slip Actuators Based On Asymmetrical Flexure Hinge

Piezoelectric stick-slip drive technology has the advantages of high positioning accuracy,large working stroke,and no electromagnetic interference.It shows important scientific significance and wide application prospects in precision optical systems,micro/nano manufacturing,and biomedical engineering.However,the existing piezoelectric stick-slip actuators are difficult to realize the comprehensive control of the frictional force during the slow and rapid deformation driving stage,which limits the output performance and become a bottleneck problem that restricts the development of the piezoelectric stick-slip drive technology.In this paper,the asymmetrical flexible hinge mechanism is introduced into the stator structure design,so that the distribution of axial stiffness of the stator is uneven,and the excitation of the driven foot of the stator is driven by the lateral displacement.The axial contact positive pressure between the stator and the slider is adjusted.to realize the comprehensive control of the friction force in the slow and rapid deformation driving stage.The comprehensive control of the friction force improves the output force and velocity of the piezoelectric stick-slip actuators.The basic theory of piezoelectric stick-slip drive is described,including the piezoelectric effects,piezoelectric stack,and the classification of common flexible hinges.The calculation method of the right-circle flexible hinge is analyzed.By using the dimensionality reduction method(MDR)to accurately convert the three-dimensional contact problem between the stator and the slider into a one-dimensional contact,the contact and friction simulation can be quickly calculated,and the theoretical model and expression of the horizontal and axial forces force are established based on the MDR method.The structure design of the piezoelectric slip-slip actuator prototype was carried out.The design of the maximum lateral displacement generated by the flexible hinge mechanism was considered as the design goal.The reasonable position of driven foot of the asymmetric flexible hinge was analyzed,and the optimal size of the asymmetric flexible hinge was achieved through static structural analysis.The stick-slip contact state during the contact process and the positive pressure change were also analyzed.The prototype of the piezoelectric stick-slip actuator was developed.The prototype was consisted of a stator,a slider,a base,and a preload mechanism.The core part stator was mainly composed of an asymmetrical flexible hinge mechanism,a piezoelectric stack,a shim block,and a preload screw.The overall size of the asymmetric piezoelectric stick-slip actuator is about 179 mm×75 mm×37.5 mm.To investigate the output performances of the proposed actuator,an experiment system has been established.The testing results show that the asymmetric piezoelectric stick-slip actuator has an optimal operating frequency of 500 Hz,a maximum output speed of 5.96 mm/s,a minimum displacement resolution of 50 nm and a maximum load of 3 N under open-loop conditions.In addition,the dynamic model of the actuator was established based on the MDR method,and the vibration amplitudes of the driving foot in the horizontal and axial directions were tested.The simulation results and experimental results of the MDR method were compared and verified,and the feasibility of the MDR method for the dynamic model of the proposed stick slip actuator was validated.In this paper,the asymmetric flexible hinge mechanism is combined with the piezoelectric stack to control the friction force,which widens the structure of the piezoelectric stick-slip actuator.This paper provides some guidance for the design and manufacture of asymmetric type stick-slip actuators,and it can provide theoretical and experimental basis for improving the output performance of the piezoelectric stick-slip actuators.