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.     

基于电流变阻尼超精密气浮工作台建模及控制研究

随超精密装备加工精度和生产率的不断提高,直线气浮系统得到广泛重视和研究。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;建立了气浮工作台整体模型并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;分别对零电场线性及高电场非线性电流变阻尼2种情况下的气浮工作台应用误差积分LQR控制器;为达到综合最优,进一步提出开关及滑模控制器,实验证实这2种控制策略均能同时提高系统的响应速度、减少建立时间,降低跟踪误差及纹波。     

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。     

Expressions for coefficients of electrorheological fluid dampers

Useful expressions are developed for the damping coefficient of two types of viscous dampers that contain electrorheological (ER) fluids. The damping action in the first type occurs in flow between stationary parallel plates; the second type has annular flow between two stationary concentric cylinders. For ER fluid control, an electric field is applied across the gap in which the fluid flow occurs. The solution for the concentric cylinder damper is based on a thin gap approximation. These solutions may facilitate solving mechanical systems problems, using ER fluids, and demonstrate the controllability of ER dampers.     

Effect of lubricants and additives on the tribological performance of solids. Part 2. Active friction control

The paper presents an analysis of the state of the art in the study of the effect of magnetic and electric fields on lubrication and active control over the friction of solids. The lubricity of magnetic and electrorheological fluids is shown to depend greatly on the properties and component composition of fillers and to be related to the provision of the required rheological characteristics (varying over a wide range), which affect the lubricating film thickness. It is noted that the application of structural-sensitive LC systems and materials in joints is a promising method for the active and effective control over their friction.     

双筒单出杆式磁流变阻尼器力学特性研究

介绍了一种基于流动模式的双筒单出杆式磁流变阻尼器结构和工作原理,推导了其阻尼力公式。对基于上述结构的MRF阻尼器的阻尼力、电流、位移、速度和频率等力学特性进行了试验研究。结果表明流动模式磁流变阻尼器的阻尼力随控制电流的增大呈非线性增加,其耗能减振能力优于传统的被动阻尼器。气囊导致压缩行程终点阻尼力放大,并可以在一定程度上消除复原行程的空程现象。而阻尼器的结构尺寸和所选用的磁流变液一旦确定,其可调倍数只依赖于最优的磁路设计。通过深入分析该型阻尼器的动力特性,为改进研制装甲车辆磁流变减振器奠定了基础。     

直联压缩机两种不同控制方法的比较研究

建立了空压机的负载数学模型,对其负载进行了分析。建立了永磁同步电机的数学模型,给出了一种用于交流永磁同步电机速度控制的滑模控制器。根据永磁同步电机的控制特点和空压机负载特点进行Simulink仿真,仿真结果表明,加滑模控制器时,电机转速波动较小。最后,对用永磁同步电机驱动直联便携式空压机做实验。实验结果表明,与常规的PI控制策略相比,滑模变结构控制改善了系统的动态性能,有较强的鲁棒性。永磁同步电机驱动空压机效率高,转速波动小。     

悬架不确定性的滑模半主动控制分析

在电流变液特性试验的基础上,提出基于电流变阻尼悬架的滑模半主动控制。依据滑模控制理论,采用极点配置法确定滑模切换面参数,应用比例切换的控制方法和等速趋近率确定控制律并改善滑模运动的动态品质,同时采用RBF神经网络算法优化滑模控制效果。针对悬架质量参数和车速不确定性,运用MATLAB/SIMULINK进行了悬架半主动控制的建模和仿真分析。仿真结果显示,与被动悬架相比基于RBF神经网络的滑模半主动控制能有效改善悬架性能,对于悬架的不确定性有较好的自适应性。     

简式液阻减震器的阻力特性及发展状况

本文介绍了目前使用在车辆上的各种不同形式结构的减震器,分析了橡胶减振器、金属弹簧减振器、电流变液和磁流变液减振器、气体控制阻尼可调减振器、干摩擦式阻尼可调减振器等的架构特点、工作原理、适用场合及其优缺点.给出了双筒液压减震器的复原阻力与压缩阻力的计算方法,为液阻减震器的设计制造提供了方便的理论基础.最后分析了我国筒式液阻减震器技术的发展状况及问题,展望了减震器技术的前景.     

基于电流变效应的阀控系统研究

以液压控制理论为基础，以电场作用下表现为Bingham模型特征的电流变液体为工作介质对基于电流变效应的阀建立控制方程，对阀控缸系统进行动静态性能分析与仿真。首次建立以蠕动泵为动力源的基于电流变效应的单元件阀性能测试回路系统试验装置，并对该系统回路进行试验研究。理论分析与试验研究结果表明，影响电流变阀控系统的主要因素是电流变材料的性能参数和电极控制尺寸，基于电流变效应的阀的响应时间在毫秒量级之内。     

压电陶瓷与电流变液结合的声学与振动控制系统

通过分别制备高性能压电陶瓷FD3-PZT,FD4-PZT和复合电流变液并测量它们的性能之后,研究和制作了由压电陶瓷与电流变液结合的一种新型声学与振动控制系统(在该系统中的压电陶瓷与电流变液之间连接有一高压延迟电路).当外界施加一个瞬时冲击力作用于该新型声学和振动控制系统中的压电陶瓷上时,压电陶瓷由于压电效应产生瞬时高压(d-c current)输入复合电流变液,电流变液在短时由于其具有的流变性(其电致流变性可逆)而迅速由液态变为固态,从而抵消了外来的瞬时冲击力.该新型声学与振动控制系统在振动控制和声学方面极有应用前景,例如抗(防)次声、声震波和爆炸冲击波的危害以及用于制造高效防弹衣、防护头盔(安全帽)等;在声学方面可制备新型电控激励器、制动器、强振隔离体、无后坐力装备及各种抗震、减振、防噪所需装置等.     

超精密气浮定位平台动力学特性分析

设计了一种超精密气浮定位平台,并运用Ansys对导轨和滑台分别作了有限元模态分析,校核了其动态刚度。在此基础上,分析了导轨的厚度对导轨刚度的影响以及滑台顶板厚度对滑台刚度的影响,为结构的优化设计提供了参考依据。分析结果显示,定位平台的刚度满足设计要求。     

Adaptive sliding mode current control with sliding mode disturbance observer for PMSM drives

This paper focuses on the current control of a permanent magnet synchronous motor (PMSM) for electric drives with model uncertainties and external disturbances. To improve the performance of the PMSM current loop in terms of the speed of response, tracking accuracy, and robustness, a hybrid control strategy is proposed by combining the adaptive sliding mode control and sliding mode disturbance observer (SMDO). An adaptive law is introduced in the sliding mode current controller to improve the dynamic response speed of the current loop and robustness of the PMSM drive system to the existing parameter variations. The SMDO is used as a compensator to restrain the external disturbances and reduce the sliding mode control gains. Experiments results demonstrate that the proposed control strategy can guarantee strong anti-disturbance capability of the PMSM drive system with improved current and speed-tracking performance.     

电流变效应在抑制车削振动中的应用

利用电流变效应设计制造了车床活顶尖电流变减振器,在减振器的活动电极板与固定电极板间注满电流变液。计算机模拟和切削试验结果表明,采用电流变减振器,可以使车床尾座活动顶尖的振动响应幅值减小约３０％。     

聚吡咯在几种连续介质中的电流变效应

研究了聚吡咯在液体石蜡、硅油和蓖麻油中的电流变效应。结果表明：随着电场强度、聚吡咯浓度的增加，电流变液的漏电流增大，而随着剪切速率的减小，漏电流却增大。由蓖麻油和聚吡咯组成的电流变液的电流变效应最好。     

半主动直接输出反馈变结构控制电流变阻尼器减振研究

针对多层结构电流变阻尼器减振系统运动状态难以完全实时测量、扰动存在不确定性、系统参数容易出现摄动以及阻尼器连续可调的特点,提出了半主动直接输出反馈变结构控制策略,根据滑模运动方程稳定的Hurwitz判据选择滑模梯度参数,实现控制与扰动完全解耦;饱和非线性环节使阻尼器阻尼力不超调;阻尼力对主结构做负功控制规则保证主结构最佳减振。仿真分析表明,电流变阻尼器减振控制系统效果明显,不仅对扰动具有自适应性,而且对系统参数摄动也具有很强的鲁棒性。     

磁流变液阻尼器-柔性转子系统振动特性与控制的再研究

对先前提出的理论分析模型进行适当改进，用新模型对支承在磁流变液阻尼器上的单盘悬臂柔性转子系统的振动特性和控制技术进行再研究。研究表明，随着磁流变液阻尼器的库仑阻尼力的增大，系统在无阻尼临界转速处振幅明显下降，但在两阶临界转速之间的一定转速区振幅增加；同时，随着库仑阻尼力的增加，阻尼器轴承处的振幅在几乎所有转速时都被减小，甚至在某些转速区间该轴承被“锁住”，而且轴承能够振动的区间越来越窄。这说明转子系统从一个弹性支承系统逐步转化为一个准刚性支承系统，阻尼器支承的有效刚度越来越大，使得一阶有阻尼临界转速逐渐提高，并逐渐接近刚支临界转速。根据这些特性，提出通过开关控制抑止转子通过两阶临界转速过程中的振动，并使转子振幅在全转速区达到最小。仿真结果表明，系统能平稳通过两阶临界转速。     

Vibration analysis on the rolling element bearing-rotor system of an air blower

Air blowers are widely used in industry. The vibration of the rolling bearing-rotor is a key factor in the blower’s performance because it significantly influences the security and working life of the whole system. In previous research on the vibration characteristics of the air blower, the supporting rolling element bearing was always simplified as a particle on a shaft with radial stiffness and damping coefficient. Such simplification neglects the effects of the bearing structure on the vibration performance of the rotor system. In this paper, a numerical model of the bending stiffness of the tapered roller bearing was established through mechanics and deformation analysis. On the base of the model, a new TMM (transfer matrix method) for bearing-rotor system was established; the new TMM considers the influences of the bearing structure on the vibration of the rotor system. Furthermore, modal analysis on an air blower rotor system was carried out by using the new TMM, and the mode shape, critical speed and unbalance response of the air blower system were obtained. The same blower rotor was also analyzed by FEM to verify the validation of the new TMM, showing that the new method proposed in this paper for vibration characteristics calculation of an air blower is credible.     

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.     

潜艇浮筏隔振系统的半主动模糊滑模控制

对带有电流变液智能阻尼器的双层浮筏隔振系统设计一种半主动静态输出反馈模糊滑模控制器.根据滑模运动方程稳定的Hurwitz判据选择滑模面矩阵.根据滑模到达条件及可控屈服阻尼力对隔振系统做负功原理设计半主动输出反馈模糊滑模控制器.仿真分析浮筏隔振系统在扫频激励信号下的力传递率及在双频激励信号下的输入力和输出力曲线.仿真结果表明,半主动输出反馈模糊滑模控制下的浮筏隔振系统的减振效果要远好于最优被动阻尼系统.