基于电流变阻尼超精密气浮工作台研究

为解决直线气浮系统抗干扰能力较差等问题,针对已开发的超精密直线气浮工作台,设计了电流变剪切模式阻尼器;基于屈服前后平滑过渡的Eyring连续本构模型通过辨识得出电流变剪切阻尼器类稳态模型;从仿真和实验研究了电流变阻尼及高电场强度对直线气浮工作台模态的影响,实验模态结果验证了仿真方法的有效性,同时证实设计的电流变阻尼器及电场强度的提高不会造成模态频率的下降,只会引起阻尼比的大幅度提高,甚至减少模态阶数。     

基于腹底式被动阻尼器抑制精密气浮工作台的定位噪声

针对已开发的精密直线气浮工作台,设计了腹底式被动结构的阻尼器以解决静压气浮导轨传动阻尼小,抗干扰能力差等问题。设计的阻尼器由固定于气浮滑套下端面的阻尼片以及处于阻尼片正下方的阻尼油槽和阻尼油组成。通过实验获取了阻尼器的阻尼系数,继而建立了气浮工作台机电控制模型。仿真分析了阻尼器对工作台气浮噪声和动态特性的影响规律:随着阻尼的增大,气浮工作台的稳定裕度和衰减噪声的能力增加,但动态响应速度降低。实验表明,实验结果与所推导的气浮工作台特性一致,且增加阻尼系数为293.78N/m.s-1的阻尼器后,气浮工作台的定位噪声由60nm(峰峰值)降为20nm(峰峰值),位移灵敏度为20nm,实验验证了采用此种结构的阻尼器可有效抑制精密气浮工作台定位噪声。     

基于静压气浮导轨的直线电机高性能工作台的研制

精密定位技术是精密工程领域的关键技术,由直线电机驱动的气浮直线导轨工作台在超精密运动领域得到广泛应用。本文介绍了静压气浮导轨的设计方法,开发了止推气浮轴承设计软件;为了提高气浮导轨的承载能力和刚度,总结提出了几种适用于不同结构气浮导轨的预加载技术;运用气浮轴承设计系统和适合的预加载技术,研制了能满足大惯量、高速度、高精度要求的H型直线电机气浮工作台。     

精密高刚度二维气浮工作台的设计与分析

目前精密二维气浮工作台的研究,存在着二维气浮工作台的刚度和承载力较小的问题,设计了一种以精密方箱为基准的精密高刚度二维气浮工作台。该气浮工作台采用整体式气浮导轨副设计,全部构件以精密方箱为位置基准,用精密方箱自身的高平面度、平行度和垂直度来保证X轴和Y轴导轨的运行直线精度和系统刚度,并且工作台采用直线电机驱动,消除了传统机械传递带来的误差。该实验台具有机械精度高、运动直线度高、系统刚度大、安装维护容易等特点,能在精密加工、精密测量领域中广泛使用。     

基于ERF的切削颤振控制建模与仿真的研究

针对电流变阻尼器抑制切削颤振存在的困难,设计了一种流动与剪切混合模式的电流变阻尼器。介绍了电流变液及电流变阻尼器的工作原理和性能特点;基于Bingham塑性理论,建立了流动与剪切混合模式的电流变阻尼器的力学模型。实验与仿真结果表明,电流变阻尼器能很好地实现振动的实时控制,并能有效地抑制切削颤振的发生。     

基于ERF的切削颤振控制建模与仿真的研究

针对电流变阻尼器抑制切削颤振存在的困难,设计了一种流动与剪切混合模式的电流变阻尼器.介绍了电流变液及电流变阻尼器的工作原理和性能特点;基于Bingham塑性理论,建立了流动与剪切混合模式的电流变阻尼器的力学模型.实验与仿真结果表明,电流变阻尼器能很好地实现振动的实时控制,并能有效地抑制切削颤振的发生.     

电流变液体阻尼器数学模型研究

分析了电流变液体(ERF)阻尼器的工作原理，建立了它的数学模型。描述了电流变液体阻尼器阻尼力与控制电场之间的关系。在理论上将压降△p分成流体黏性阻尼引起的和有控制电场引起的两部分。该模型为电流变液体阻尼器的力学分析和计算提供了理论基础。     

电流变技术在机床切削颤振控制中的应用

根据电流变液体的优良力学性能和剪切模式电流变液阻尼器的工作原理,设计了一基于剪切模式的电流变阻尼器,在此基础上设计了一个颤振控制专用刀座系统.对这个系统进行了动力学模型的建立和分析,最后通过计算机仿真表明通过控制电流变阻尼器的电场强度可以很方便地调节系统的阻尼率,大幅度地减小振幅,能有效地抑制切削颤振的发生.     

基于ER阻尼的WEDM电极丝恒张力微机控制

电流变液是一种可控智能阻尼介质,其表观粘度和剪切屈服应力随外加电场发生快速变化。设计了一种以ER阻尼器为执行元件的恒张力微机控制系统,系统响应快,较好地解决了电火花线切割加工过程中的张力测量和控制精度问题,实现了电极丝的恒张力控制。     

直线电机精密工作台扰动观测器设计

针对直线电机驱动、气浮导轨支撑的精密工作台没有机械阻尼、抗扰动性能差的特点,为了在较短的位置伺服周期内(110μs)抑制工作台上的线缆扰动以及直线电机推力波动的影响,提高工作台的轨迹跟踪精度,采用了基于精密工作台名义模型的方法设计扰动观测器,构成PD+扰动观测器的运动控制结构。通过实验,与没有扰动观测器的PD控制相比较,工作台静态定位精度提高了0.3μm,以120 mm/s匀速运动时工作台的轨迹跟踪精度提高了2μm。结果表明,该控制方法计算量小,抑制外部扰动效果好,有利于工作台综合性能的提高。     

Electrorheological damper for the ultra-precision air bearing stage

This paper illustrates how the electrorheological damper substantially improves the performance of the ultra-precision air bearing stage. Smart materials such as electrorheological fluids have attracted many researchers’ attention because of their resistance changeable performance in different electric fields. Meanwhile, the ultra-precision air bearing stage driven by the linear-motor is characterized by zero mechanical damping and poor anti-disturbance. To solve this problem and consider the characteristics of electrorheological fluids, an electrorheological damper is proposed in this paper. The electrorheological damper’s characteristics in high electric fields are obtained based on the Eyring constitutive model, which smoothly transits from the pre-yield to post-yield region. To enhance the performance of the electrorheological damper, which takes effect only when the stage is going to decelerate or position, the on-off and sliding mode control methods design and optimize the controller. The results prove that by using the advanced sliding mode control method, the characteristics of the ultra-precision air bearing stage can be effectively improved through the introduction of the electrorheological damper.     

Electrorheological damper for the ultra-precision air bearing stage

This paper illustrates how the electrorheological damper substantially improves the performance of the ultra-precision air bearing stage. Smart materials such as electrorheological fluids have attracted many researchers’ attention because of their resistance changeable performance in different electric fields. Meanwhile, the ultra-precision air bearing stage driven by the linear-motor is characterized by zero mechanical damping and poor anti-disturbance. To solve this problem and consider the characteristics of electrorheological fluids, an electrorheological damper is proposed in this paper. The electrorheological damper’s characteristics in high electric fields are obtained based on the Eyring constitutive model, which smoothly transits from the pre-yield to post-yield region. To enhance the performance of the electrorheological damper, which takes effect only when the stage is going to decelerate or position, the on-off and sliding mode control methods design and optimize the controller. The results prove that by using the advanced sliding mode control method, the characteristics of the ultra-precision air bearing stage can be effectively improved through the introduction of the electrorheological damper.     

STUDY ON ELECTRORHEOLOGICAL FLUID DAMPER FOR APPLICATION IN MACHINING CHATTER CONTROL

The electrorheological fluid(ERF)is a kind of intelligent material with bright prospects for industry applications, which has viscoelastic characteristic: under the applied electric field. The dynamic model of a milling system with an ERF damper is established, and the chatter suppression mechanism of the ER effect is discussed theoretically. Both the theoretical study and the experimental investigation show that the additional damping and additioaal stiffness produced by the ERF increase with the rise in the strength of electric field E, but their influence on the cutting stability is different. Only when both additional damping and additional stiffress cooperate, the milling chatter can be suppressed quickly and effectively. In additional, an ERF dumper used on the arbor of horizontal spindle milling machine is developed, and a series of milling shatter control experiments are performed. The experimental results show that the milling chatter can be suppressed effectively by using the ER damper.     

Nano positioning control for dual stage using minimum order observer

A nano positioning control is developed using the ultra-precision positioning apparatus such as actuator, sensor, guide, power transmission element with an appropriate control method. Using established procedures, a single plane X-Y stage with ultra-precision positioning is manufactured. A global stage for materialization with robust system is combined by using an AC servo motor with a ball screw and rolling guide. An ultra-precision positioning system is developed using a micro stage with an elastic hinge and piezo element. Global and micro servos for positioning with nanometer accuracy are controlled simultaneously using an incremental encoder and a laser interferometer to measure displacement. Using established procedures, an ultra-precision positioning system (100 mm stroke and ±10 nm positioning accuracy) with a single plane X-Y stage is fabricated. Its performance is evaluated through simulation using Matlab. After analyzing previous control algorithms and adapting modern control theory, a dual servo algorithm is developed for a minimum order observer to secure the stability and priority on the controller. The simulations and experiments on the ultra precision positioning and the stability of the ultra-precision positioning system with single plane X-Y stage and the priority of the control algorithm are secured by using Matlab with Simulink and ControlDesk made in dSPACE.     

基于电流变效应的车削颤振预报控制技术的研究

将电流变减振技术引入机床切削系统,研制了车床横刀架电流变液减振器。通过流变学动态模量测试方法,求得了该系统的附加阻尼和附加刚度,并对该系统振动响应特性进行了理论分析。研制开发了基于电流变效应的车削颤振预报控制系统。预报控制试验结果表明,利用该系统可以对机床切削颤振实施有效的预报控制。     

直线电机驱动的H型气浮导轨运动平台

建立了双边直线电机驱动的H型气浮精密定位平台,对该精密定位系统的气浮导轨设计方法和双边直线电机同步运动控制等关键技术进行了研究。利用有限元法设计了气浮导轨,分析了气膜压力场的分布情况,采用预加载技术提高气浮导轨的承载能力和刚度等性能。静态特性实验表明,开发的定位平台气浮导轨具有较高的承载能力和刚度,X、Y导轨的竖直方向静刚度为276.9 N/μm和333.3 N/μm。设计了基于同步速度偏差的改进型并联结构同步控制器,采用模糊控制实现PID参数的自适应在线整定。运动实验表明,改进的控制器具有较高的同步控制精度,速度同步精度比一般同步控制提高了3倍多,适合于具有强机械耦合的多电机同步运动控制。H型直线电机气浮定位平台具有承载能力强、精度高的优点,可以用于光刻机和光学检测等精密工程领域。     

电流变阀外置的汽车双筒液力减振器的理论及试验研究

介绍了电流变阀外置的新型汽车减振器的理论、结构及试验研究。阐述了电流变液体减振器阻尼力和电场的关系,其阻尼力由两部分组成:一部分是由粘性阻尼引起的牛顿力,无电场作用时,作为普通的减振器用;另一部分是由所加电场引起的切应力,它与所加电场强度成正比。试验结果表明:所设计的新型汽车电流变液体减振器具有阻尼力变化大、响应快、控制容易、结构简单和能源消耗低等特点,满足了汽车工程的实际需要,具有重要工程实用价值。     

电流变材料抑振机构动态性能测试与分析

电流变材料在振动控制中表现出优良的阻尼抗振性能,但由于电流变材料在振动结构中随振动幅度、振动频率和施加电场强度的变化,其动态性能表现出明显的差异,使控制模型难于准确制定。通过对含有电流变材料的抑振机构进行动态性能测试试验,获取在不同电场强度和不同激振频率下的迟滞曲线,并结合所建立的迟滞曲线数学模型将电流变材料在结构振动控制中所表现出来的动态性能分为牛顿粘性液体、屈服前弹性体、屈服前粘弹体、非线性体和屈服后粘性体,同时,分析了电流变材料不同动态特性出现的条件及其对整个结构动态性能的影响。这种试验分析方法为有效制定电流变抑振机构的控制策略提供了科学依据。     

电流变液减振器在抑制深孔切削颤振上的研究

针对深孔机床切削中的颤振问题,设计了一套基于流动模式的电流变液减振器,分析了电流变液减振器的阻尼力并得出其表达式;又通过对切削颤振产生原因的分析,推导出瞬时动态钻削力的表达式;并在研究了深孔机床切削过程的基础上,建立了切削系统动力学模型,得出安装电流变液减振器后的动力学方程。在给定动力学方程中的参数值后,通过计算机仿真,对比安装和未安装电流变液减振器后的振动时域图,时域图表明电流变液减振器能有效地抑制深孔机床的切削颤振。