Coupling Error Analysis Of Flexure Based Compliant Motion Stage

The progress and development of science and technology makes the flexible unit play an increasingly important role in medical,biological and material fields.The main form of the flexible element is the flexure hinge.From the initial arc-shaped flexure hinge began,through the tireless efforts of researchers,flexure hinge has evolved a different shape,multiple degrees of freedom and other flexible hinges.A mechanism made up of flexible units is called a flexible mechanism.The flexible mechanism extends from the original single-degree-of-freedom structure to the present multi-free structure,extending from one-dimensional plane to three-dimensional plane.The common types of flexible mechanism are serial,parallel,mixed and other structural forms.Flexible mechanism can be combined to constitute a flexible motion stage.For flexible motion stages,the main factors that affect their motion accuracy are coupling error,hysteresis,vibration and so on.Among them,the coupling error has the greatest influence,and the proportion is more than 60%.Coupling error is the most important factor affecting the accuracy of flexible motion stage,because it can not be accurately measured and the composition are complex,so coupling error is difficult to solve.In this paper,the analysis of coupling error,the establishment of error model and coupling error compensation are the main three aspects,the specific research work is as follows:(1)A compliant motion stage driven by piezoelectric ceramics was designed.Based on this stage,the coupling characteristics of the flexible motion stage were studied.In the compliant stage,a new cross-shaped flexible hinge structure was adopted as the motion decoupling mechanism to improve the accuracy of the movement stage;the compliant lever amplification mechanism with symmetrical layout are used to increase the stroke of the stge.(2)The motion coupling error of the compliant motion stage is analyzed.In the compliant motion stage,the coupling error is mainly related to the decoupling mechanism.The compliant stage is modeled by the method of compliant matrix.The input stiffness and output stiffness are analyzed.The coupling error of the compliant stage is defined,and the calculation method of the structural coupling error is given.(3)Considering the different temperature load of the precision compliant stage in the engineering application,the finite element method is used to establish the model of the thermo-solid coupling error under the condition of temperature load.This paper analyzes the coupling error of the precision compliant stage under different temperature loading conditions.(4)Finally,a series of tests were carried out using the compliant stage prototype,which verified the correctness and validity of the coupling error theory model.Respectively,completed the stiffness test of the cross flexible hinge,the decoupling performance test of compliant stage and the test of the thermal structure coupling.