【作者】 姜文锐；

【导师】 卢泽生；

【作者基本信息】 哈尔滨工业大学 ， 机械制造及其自动化， 2009， 博士

【摘要】 随着科学技术的不断发展,在国防工业、航天宇航技术、生物工程、微电子工程、纳米科学与技术等各个领域,对加工精度的要求越来越高,提高制造精度后可以大幅地提高产品的性能和质量,提高其稳定性和可靠性。超精密机床是保证产品加工精度的主要工具,而微进给系统作为超精密机床的核心部件,其性能直接影响超精密机床的加工精度。超精密加工技术的持续发展,要求进给系统能够实现在大行程范围内的超精密微位移,从而可以加工大尺寸的工件,并获得好的加工精度。传统的进给系统受自身结构特点的限制,不能很好地满足要求,因此需要研制一种新型的具有高精度、大行程的超精密进给系统,可以大大提高超精密机床的加工精度。对提高我国国民经济发展、缩短我国与发达国家在超精密加工、检测领域的差距,加快国防工业现代化建设具有重要意义。本文基于摩擦学原理,采用压电陶瓷驱动,研制了一种新型的大行程高精度微进给系统,为超精密微进给技术的实现提供了一个经济可靠的手段,对于超精密定位系统的研究和应用具有重要的意义和实用价值。该微进给系统由驱动部件与传动部件组成。驱动部件采用压电陶瓷驱动摩擦套筒实现角位移输出;传动部件由滚珠丝杠与空气静压导轨组成,实现直线运动。对系统的可调预压装置、空气静压导轨等关键部件进行设计,采用有限元方法系统地分析了预压装置的刚度、应力、固有频率等静态特性,得出柔性铰链的各几何尺寸对预压装置的静态特性的影响,从而实现优化设计。采用模块化方法,建立微进给系统的物理模型和数学模型,为设计系统的控制器打下了基础。为了减少摩擦驱动过程中,微观滑移、非线性等因素对定位系统的动态性能的影响,优化控制系统的控制参数,建立了系统的动力学模型与方程,并基于Karnopp“粘滞——滑移”模型对系统的动态特性进行仿真、实验研究,得出正压力、摩擦系数、转动惯量等参数变化对位移输出的影响规律。针对压电陶瓷驱动过程中存在的磁滞、非线性等特性,建立了驱动系统的逆Preisach模型,能够很好的预测压电驱动器在经过一定的随机控制电压序列后的位移输出值,有效地改善输出位移的磁滞非线性,减小了系统的非线性误差,提高了控制精度。根据微进给机构的特点,设计了变速积分模糊控制系统。采用二维模糊控制器,在选择模糊变量的隶属函数时采用不均匀划分,在误差较大的区域采用低分辨率的模糊子集,在误差较小的区域采用较高分辨率的模糊子集,从而提高系统的渐进稳定性,并改善了常规模糊控制器存在量化误差和调节死区、稳态性能差的缺点。采用Matlab软件的Simulink工具进行了闭环控制的仿真分析,证明了方案的可行性。通过对所设计的微进给机构进行闭环控制的实验研究,能够在150mm的行程上,得到高精度的位移输出,位移分辨率可达到0.01μm,定位精度达到0.0347μm。通过实验研究了实验参数对系统的动态性能的影响规律,验证了仿真结果,得出优化控制参数。更多还原

【Abstract】 With the development of science and technology, the requirement of machining precision is becoming higher and higher in all kinds of fields, such as national defense industry, navigation technique, biology engineering, micro-electron engineering and nanometer science and technology and so on. The capability and quality, stability and dependability of products can be improved greatly by enhancing fabricate precision. Ultra-precision machine tool is a major tool to ensure machining precision of products. Micro-feed system is the core part of ultra-precision machine tool, whose capability determined directly machining precision. With the development of ultra-precision machining technology, ultra-precision positioning in the range of large displacement needs to be achieved in micro-feed system to machine workpiece with large size and obtain the good machining precision. Traditional feed system can not satisfy requirement of machining precision, which is limited by its characteristic of structure. So a new ultra-precision feed system with high precision and large travel needs to be designed and fabricated, consequently the machining precision of ultra-precision machine tool is improved greatly, which has important significance to improve national economy, shorten the gap of ultra-precision machining and detection between our country and developed countries and accelerate national defense industry modernization construction.A new micro-feed system with large-travel and high-precision based on tribology theory is presented, which is driven by piezoelectric actuators. It provides an economy and reliable method for the realization of nanoposition technique, which has important significant and practicality value on the research and application of ultra-precision positioning system.The micro-feed system consists of driving parts and transmission parts. The friction column is driven by piezoelectric actuator to obtain the output angle displacement in driving parts; Transmission parts consist of ball screw and air static guide, which achieve linear motion. The key parts of system are devised, which consist of adjustable preload mechanisms and air static guide. The static characteristics of preload mechanisms that consist of stiffness, stress and natural frequency are analyzed by finite element analysis method to obtain the physical dimension of flexibility hinges influence on static characteristics. And optimum design is achieved.Physical and mathematic model of micro-feed system are built by modularized method to provide theory basis for devising controller of this system. Dynamics model and equation are built in order to optimize control parameters and reduce influence factors on positioning system during friction drive, such as micro-slip, nonlinear and so on. Simulation and experimental research on dynamic characteristic of system is carried out based on Karnopp“stick-slip”model. The influence rule on dynamical characteristic is obtained which is aroused by normal pressure, friction coefficient and rotary inertia.Inverse Preisach model of driving system is built to describe hysteresis and nonlinear characteristic existing in piezoelectricity. The output displacement is predicted perfectly after a series of random voltage path. And hysteresis nonlinear of displacement is improved availably. The nonlinear error is reduced and control precision is increased.Fuzzy control system with variable speed integrate is designed according to the features of micro-feed mechanism. Two-dimension fuzzy controller is adopted. Non-homogeneous division is adopted to choose membership function of fuzzy variable. Fuzzy subset with low precision is adopted when the error is large. Otherwise fuzzy subset with high precision is done. The disadvantages of quantization, dead zone and bad steady-state behavior which exist in conventional fuzzy controller will be ameliorated, and stability of the system is improved. The simulation of closed-loop control is done by Simulink in Matlab software, which proves that the project is feasible. Experimental research on closed-loop control is carried on. The precision ofthe micro-feed motion is 0.01μm in the travel of 150mm, and positioning precision is up to 0.0347μm. The impact rules of experimental parameters on dynamic characteristic are investigated by experimental method. The result is same to simulation, and optimizing control parameters are obtained.更多还原