| Micro-displacement positioning platform is widely used in ultra-precision machining,micro-motor system,optical technology,nanotechnology,and white light interferometer.The proposed and designed micro-displacement positioning platform with compact structure,large stroke,small stroke resolution,and response speed block has become an important indicator to measure the level of industrial development.In this thesis,aiming at the problems of small displacement and low travel accuracy of the micro-displacement positioning platform of the white light interferometer new-view 200,the micro-displacement positioning platform is studied and a micro-displacement positioning platform is innovatively designed.Firstly,a two-stage amplification mechanism of leverage displacement based on a flexible mechanism is proposed.In this structure,the output displacement of the piezoelectric ceramic is amplified,and according to the overall size of the micro-displacement positioning platform is limited,the wedge mechanism and the piezoelectric ceramic are used in the form of coordination,and the piezoelectric ceramic is placed horizontally.The transverse output displacement of the piezoelectric ceramic is converted to the displacement in the vertical direction by the wedge mechanism,and the pseudo-rigid body model is established.The kinematics model is established by using the vector closed-loop method.The magnification of the lever displacement secondary amplification mechanism is obtained,and the deflection between each rod is analyzed.Secondly,the micro-displacement platform of the micro-displacement positioning platform is designed based on a lever displacement amplification mechanism and biaxial hinge,and the output displacement of the micro-displacement platform is analyzed theoretically.The designed micro-displacement positioning platform adopts an asymmetrical structure.To simplify the calculation,a part of the micro-displacement positioning platform is selected for analysis and reasonable simplification,and the vector closure equation is established.Through theoretical analysis,the Jacobian matrix of the relationship between the input and output of the micro-displacement positioning platform and the relationship between the change of the angle of the flexible hinge at the output end of the lever displacement secondary amplification mechanism and the rotation of the moving platform is obtained.The modal calculation of the whole micro-displacement positioning platform is carried out by using the Lagrange equation,the expression of its natural frequency is obtained,and the coupling displacement of the micro-displacement platform is analyzed.Thirdly,combined with theoretical calculation,using Latin hypercube and response surface method,the influence of various structural parameters on the output displacement of the motion platform was obtained.And the finite element software is used to simulate the lever displacement secondary amplifying mechanism and the micro-displacement positioning platform.By analyzing the numerical calculation and simulation results,it can be obtained that the magnification of the lever displacement secondary amplifying mechanism is 3.2 times.When the displacement of 30μm is input,the theoretical The maximum error of the calculation and simulation results is 13.4%.The output displacements of the micro-displacement positioning platform in the x-axis and y-axis directions are:-36.25μm～36.25μm and-36.25μm～36.25μm,and the accuracy is 2.2nm;The rotation angle of the shaft is:-0.01648°～0.01648°,the precision is 8’’,and the maximum error between the theoretical and output displacement is 3%.The natural frequency of the micro-displacement positioning platform in the x-axis and y-axis directions is 87.01 Hz,and the maximum error value between the theoretical and simulation results is 17.6%.The reasons for the theoretical calculation and simulation errors are analyzed,and the output displacement of the micro-displacement positioning platform is discussed.It is related to the second-level amplification of lever displacement.At the same time,the influence of the coupling displacement of the micro-displacement platform on the output displacement is also analyzed.Finally,the PID control of the micro-displacement positioning platform and the design and realization of the large stroke of the micro-displacement positioning platform are carried out.The PID closed-loop control of the micro-displacement positioning platform is carried out to further improve the response speed and stability of the system.Due to the small motion stroke of the micro-displacement positioning platform,it cannot meet the design goal.Therefore,a large stroke device of the micro-displacement positioning platform is designed.The device adopts a guide rail and a linear stepper motor.The overall design is four-layer,which meets the linear motion in the x-axis and y-axis directions,the rotation around the z-axis,and the motion around the x-axis.In theory,the displacement travel of the micro-displacement positioning platform in the x-axis and y-axis directions is-100mm～100mm,and the motion accuracy is 31.7μm.The rotation stroke around the z-axis is-23.65°～23.65°,and the accuracy is 0.015°.The rotation stroke around the x-axis is-20°～20°,and the accuracy is 30′′,which meets the characteristics of large displacement stroke and high stroke accuracy.Because the micro displacement platform designed in this paper adopts an asymmetrical structure,the output value can be positive or negative,and the design goal is completed.The research results of this paper also provide a theoretical basis for the application of lever mechanism,flexible hinge,and wedge block mechanism in other devices. |
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