| A compliant micro-positioning stage(CMS)is a type of precision mechanism that is designed to achieve stable output and positioning functions by virtue of elastic deformation from its flexible components.It’s widely applicable due to many characteristics,such as no clearance,no frictional wear and high service life.Thanks to its excellent performance,a planar CMS is typically used in high tech fields such as precision measurement systems,nanotechnology,microscopy and semiconductor manufacturing as a core component.It is always the focus of this field that how to achieve performance analysis and structure design of a planar CMS with excellent static and dynamic characteristics.Based on the above research background,this paper conducts the following research:(1)Firstly,to solve the problem of the CMS’s dynamic equation which is difficult to establish and solve,Transfer Matrix Method(TMM)is introduced to studying the dynamics of platforms.The vibration model will be established using TMM by regarding a platform as an ordered combination of some elements,such as flexible one and rigid one.Starting from the concepts of state vectors and element transfer matrices,the matrices of flexible beams,circular hinges and two types of rigid elements with different input-output characteristic are derived.A cantilever beam model is proposed to verify these matrices by FEA,the results show that the relative error of natural frequency between theoretical and simulated values is less than 1.13%,and the two have the same vibration mode,which preliminarily verifies the feasibility of studying dynamics of CMS using TMM.(2)Then,a comparative analysis of series,parallel,and hybrid structures is performed to determine the research type and design principle of a high-performance planar CMS.By studying some main configuration methods of flexible mechanisms,an approach for planar CMS design is proposed.Based on FACT method,an initial structure of the platform with a novel compliant motion pair which has 1T degree of freedom.Two different types of highperformance CMSs are realized through optimizing the structure of the pair and platform mentioned above from the perspective of reducing motion loss and improving natural frequency,respectively.(3)Next,a dynamic model is established for a 4-PP CMS based on a reverse-series connection motion pair.Starting from its driving pair,the overall transfer equation is deduced by TMM through analyzing the serial-parallel relationships between each unit,pair and limb.The platform’s natural frequency and transient dynamic response are analyzed accordingly.Its comprehensive performance is studied by FEA which is used to verify that the structure optimization is effective compared to the initial structure stage mentioned above.The theoretical values of the first two natural frequencies are both 192.67 Hz,with the relative errors no more than 2.4%.The displacement response curves with 0.1s along the x and y directions,which are consistent with theoretical expectations,are similar to the results from FEA.Both the static and dynamic performance of the platform are superior to that of the initial one,demonstrating the effectiveness of structure optimization.By discussing the factors that influence the stage’s frequency and their variation,a plan for performance optimization is proposed accordingly.(4)Finally,a 4-PP planar CMS based on symmetric parallel motion pairs is proposed to improve its ability of decoupling and dynamic performance.A research method for analyzing the comprehensive performance and parametric optimization design of CMSs is established based on this platform.The model of input stiffness and motion loss and analysis of mode and displacement response are established by using Compliance Matrix Method(CMM)and TMM,respectively.The simulation results show that the theoretical model error of the platform stiffness under a 0.3mm driving displacement is no more than 2.11%,and the lost motion is7.63μm.Based on the theoretical model above,the sensitivity relationship between the comprehensive performance and the size of the flexible elements is pointed out.On this basis,the parameter optimization of the platform is completed,which show that the first-order natural frequency of the platform after optimization is 461.06 Hz,and the lost motion is 7.58μm,which improves by 43.9% and 6.6%,respectively. |
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