Research On Linear Piezoelectric Stick-slip Actuator Based On Principle Of Hinge Displacement Amplification

With the rapid development of aerospace,micro/nano fabrication,biomedical engineering,and precision optical instruments,the demands for the performance of precision drive technology have been gradually increasing.The piezoelectric stick-slip drive technology has attracted extensive attention in recent years due to its advantages of fast response speed,no electromagnetic interference,large stroke and high accuracy.In this paper,a piezoelectric stick-slip actuator based on the principle of hinge displacement amplification is proposed.Two kinds of structures including the piezoelectric stack vertical to the guide rail and the stack parallel to the guide rail are designed to solve the problems of low output speed and suppressed reverse movement of the hinge-type single piezoelectric stack stick-slip actuator.The triangular piezoelectric stick-slip actuator has the characteristic that the deformation of long-side is larger than the deformation of short-side when the triangle is amplified,which can effectively increase the output speed of the actuator,but there exists still the problem of reverse motion suppression;the lever-type piezoelectric stick-slip actuator utilizes the feature that the direction of output force is parallel to the direction of input force when the lever is amplified,which not only increases the speed of the actuator,but makes the forward and reverse performance tend to be the same.The main research contents of this article are as follows:First of all,the basic theory of the piezoelectric stick-slip actuator is explained,including the basic knowledge of piezoelectric materials,the internal structure of the piezoelectric stack and the application of flexible hinges.The forward and reverse piezoelectric effects of piezoelectric materials and the development,classification and materials of flexible hinges are depicted.The simulation of straight circular hinges is conducted to provide a basis for the selection of hinges at different positions;the basic mechanical model of the flexible hinge is established,and the flexibility of the flexible hinge under the action of force and moment in different directions is given,which provides the theoretical support for the design and calculation of the actuator.Secondly,the structure of the piezoelectric stick-slip actuator based on the principle of hinge displacement amplification is designed.The triangle-shaped flexible hinge structure and the lever-shaped flexible hinge structure are proposed.The composition and working principle of the two actuators are analyzed.In order to achieve the maximum displacement of the driving foot in the output direction,the key parameters of the two structures are analyzed to obtain the optimal size.The results of theoretical calculations show that the two flexible hinge mechanisms design effectively achieve displacement amplification of the piezoelectric stack.And the calculation results are almost consistent with simulation results.Finally,experimental prototypes of triangular piezoelectric stick-slip actuator and lever piezoelectric stick-slip actuator are fabricated.The measurement system is constructed for the experimental research.The experimental results show that the maximum step efficiency is 97.9%,and the maximum output speed of the prototype is 20.17 mm/s when the locking force of the triangular-shaped prototype is 2.5 N.When the symmetry is 20% or 80%,and the optimal driving frequency is 480 Hz,the maximum achievable forward speed of the lever-type piezoelectric stick-slip actuator is 7.69 mm/s,and the maximum reverse speed is 7.12 mm/s.The displacement difference is 8.80 ?m per 10 cycles.Compared with the existing bidirectional motion piezoelectric actuator,there is little difference between the forward and reverse displacement.