面向光栅制造的宏微超精密进给系统的设计与研究

发布时间：2018-01-10 05:13

本文关键词：面向光栅制造的宏微超精密进给系统的设计与研究　出处：《中国科学技术大学》2014年博士论文　论文类型：学位论文

【摘要】：大型光学系统及高端科学仪器对我国科学研究、国防安全、经济建设和社会民生等各领域的进步和发展具有极其重要的作用。大面积、高精度衍射光栅则广泛应用于光学天文望远镜、惯性约束激光核聚变(ICF)装置、大型光刻系统和高分辨率中阶梯光栅全谱仪等场合。大面积、高精度光栅具有刻划幅面宽、行程长、刻槽结构复杂、槽形精度要求苛刻等特点,决定了机械刻划的制造加工方式。光栅刻划机要求在几百毫米的行程范围内,完成每毫米内几千甚至上万道刻线的刻划,并且保证很高的加工精度。同时,光栅质量与光栅刻线形态密切相关,而光栅刻线是由毛坯位置和刻刀位置共同决定,这就需要一套性能良好的超精密进给系统来完成对光栅毛坯在分度方向上的定位。针对光栅刻划的特殊需求,确定了宏微驱动的进给方式。分度系统的位移进给包括宏微驱动结构、位移测量反馈系统和计算机控制系统三个方面,针对分度系统的二级驱动模式,分析了宏驱动的丝杠螺母传动系统和微致动的压电驱动结构力学特性对系统定位精度的影响,并从状态空间角度,分析了光栅刻划机二级传动控制模型的可控性和可观性。由于宏微驱动的长传动链造成的刚度不足和间隙等问题,分析了在系统运行过程中产生的爬行现象与影响爬行的刚度、质量、摩擦系统、阻尼之间的关系。光栅刻划机微致动平台承载光栅毛坯实现分度方向上的位移进给,其定位精度直接影响着光栅的加工质量。微致动系统是基于柔性铰链的柔性机构,论文中对不同形状柔性铰链进行了对比分析,对柔性簧片进行了理论建模,基于半梁模型对微致动系统的刚度进行了分析,研究了铰链参数以及光栅毛坯质量对平台刚度的影响；同时,对微致动平台进行动力学建模,分析系统主要参数对模态的影响,并在此基础上对微致动平台关键零件柔性铰链的尺寸进行了优化。高定位精度要求的微致动平台,需要相应的控制系统。为了得到更适于光栅刻划进给系统的控制策略,就需要对系统进行辨识,从而获得相关参数。根据辨识模型的复杂性,和微致动平台本身的非线性和时变性等因素,需要控制算法在运行过程中具备一定的自学习和自适应特性。因此文中分析了基于单神经元PID和基于BP神经网络的PID控制算法的微致动进给方式,并将其定位数据与定长PID进行对比。光栅刻划控制实验研究表明,结合BP-PID自适应控制算法,工作台可实现近5nm的控制定位精度。通过对测试数据的数据统计分析,包括刻线的误差分析,验证了光栅刻划机分度进给系统控制策略选择的有效性。
[Abstract]:Large-scale optical systems and high-end scientific instruments play an extremely important role in the progress and development of China's scientific research, national defense security, economic construction and people's livelihood. High precision diffraction gratings are widely used in optical astronomical telescopes, inertial confinement laser fusion devices, large lithography systems and high resolution full-scale grating spectrometers. High precision grating has the characteristics of wide width, long stroke, complex groove structure and harsh precision requirements, which determines the manufacturing and processing mode of mechanical scribing. The grating engraving machine requires a travel range of several hundred millimeters. Complete thousands or even tens of thousands of lines per millimeter, and ensure high processing accuracy. At the same time, the grating quality and grating line shape is closely related. The raster line is determined by the position of the blank and the cutter, which requires a set of ultra-precision feed system with good performance to complete the positioning of the raster blank in the indexing direction. According to the special requirements of grating description, the feed mode of macro and micro drive is determined. The displacement feed of indexing system includes macro and micro drive structure, displacement measurement feedback system and computer control system. Aiming at the two-stage drive mode of the indexing system, the influence of the mechanical characteristics of the macro driven screw nut drive system and the micro-actuated piezoelectric drive structure on the positioning accuracy of the system is analyzed, and from the point of view of the state space, the influence of the mechanical characteristics on the positioning accuracy of the system is analyzed. The controllability and observability of the two-stage drive control model of grating engraving machine are analyzed. The stiffness deficiency and clearance caused by the long transmission chain driven by macro and micro are analyzed. The relationship between crawling phenomenon and stiffness, mass, friction system and damping is analyzed. The micro-actuation platform of the grating marking machine carries the grating blank to realize the displacement feed in the indexing direction, and its positioning accuracy directly affects the processing quality of the grating. The micro-actuation system is a flexible mechanism based on the flexure hinge. In this paper, the flexure hinge with different shapes is compared and analyzed, and the stiffness of the micro-actuation system is analyzed based on the half-beam model. The effects of hinge parameters and the quality of raster blank on the stiffness of the platform are studied. At the same time, the dynamic modeling of the micro-actuated platform is carried out, and the influence of the main parameters of the system on the modal is analyzed. On the basis of this, the size of the flexure hinge of the key parts of the micro-actuated platform is optimized. The micro-actuation platform with high positioning precision needs corresponding control system. In order to obtain the control strategy which is more suitable for grating drive feed system, it is necessary to identify the system. According to the complexity of the identification model and the nonlinear and time-varying factors of the micro-actuated platform itself. The need control algorithm has some self-learning and adaptive characteristics in the running process. Therefore, the micro-actuation feed method based on single-neuron PID and BP neural network based PID control algorithm is analyzed. The experimental results show that the BP-PID adaptive control algorithm is combined with the BP-PID adaptive control algorithm. Through the statistical analysis of the test data, including the error analysis of the marking line, the effectiveness of the control strategy selection for the indexing feed system of the grating engraving machine is verified.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TH74;TH122

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