基于电流变效应的超精密工件台研究与展望

通过分析超精密工件台系统的研究现状和存在问题及电流变液ERF的机理和应用现状,提出"基于ERF半主动阻尼的直线电机驱动-气浮/磁浮导轨"纳米级超精密工件台系统.介绍了国内外相关研究,分析了此工件台系统具有的特性及尚待解决的问题.     

用于计算机磁头驱动的新型直线超声电机

提出并设计了一种用于计算机硬盘磁头驱动的新型矩形压电复合板直线超声电机,并详细地给出了它的结构组成和运动机理分析。该直线超声电机利用了矩形板面内两种弯曲模态的合成,通过对复合振子的合理设计使两弯曲模态频率趋于一致,并通过改变驱动信号的相位差实现电机的往复直线运动。它除了具有直线超声电机的共同特点外,还具有自身的薄、小、轻、驱动力大等突出特点,可直接应用于计算机硬盘磁头驱动等外设装置中,以及其他需要高精度定位和快速响应的直线运动系统中。     

超精密定位工作台

在许多高技术领域需要超精密工作台为其技术支持。就电磁式工作台、直线电机式工作台、压电式工作台、摩擦驱动式工作台、MEMS工作台和其它类型工作台的原理、性能和应用作了介绍。并分析了它们各自的特点。根据不同的应用要求可选用合适的超精密定位方案。     

精密工作台扰动观测器的设计

针对直线电机驱动、气浮导轨支撑的精密工作台没有阻尼、抗扰性能差的特点,为了抑制各种线缆扰动和直线电机推力波动的影响,提高工作台的定位精度、减小轨迹跟踪误差,采用扰动观测方法,基于直线电机精密工作台设计了前馈 反馈 扰动观测的控制器.详细讨论了扰动观测器的设计方法.实验结果表明,采用扰动观测器后,实现了±0.15μm 的静态定位精度,以150 mm/s匀速运动时轨迹跟踪精度保持在±1.5 μm 的误差带范围内.扰动观测器能够有效地抑制低频噪声和克服参数变化的不利影响.     

光刻机掩模台宏动定位系统的控制器设计

为给步进扫描光刻机的设计研究提供理论指导,解决光刻机掩膜台宏动平台的控制问题,采用直线电机设计了高速、高精密步进扫描光刻机的掩模台模拟宏动定位系统,并建立了整个直线运动平台的数学模型。根据该系统的特点和模型,还设计了一种不完全微分PID+干扰观测器的控制方式。运用MATLAB软件进行仿真,结果表明,在具有相同的扰动下,仅采用普通PID控制,系统跟踪误差在±0.025 mm范围内变化,而采用该控制方式,系统跟踪误差在±0.015 mm的范围内变化,后者比前者具有更好的控制性能,因而可以使系统得到较好的抗干扰能力、跟踪性能和控制效果。     

直线电机和磁悬浮列车

一般电动机工作时都是转动的。但是用旋转的电机驱动的交通工具（比如电动机车和城市中的电车等）需要做直线运动，用旋转的电机驱动的机器的一些部件也要做直线运动。这就需要增加把旋转运动变为直线运动的一套装置。能不能直接运用直线运动的电机来驱动，从而省去这套装呢？几十年前人们就提出了这个问题。现在已制成了直线运动的电动机，即直线电机。     

压电陶瓷电机驱动的三维微动定位平台及验证

压电陶瓷电机具有高分辨率和压电驱动装置的动态特性,具有体积小、结构紧凑、成本低、输出力大、响应快、精度高、无电磁干扰等特点,但存在滞后误差、垂向位移误差,行程短的问题,尤其在电极损耗后,补偿量增大,严重影响了定位精度和难以满足三维加工的工作要求。该文通过对压电陶瓷电机驱动的百毫米以上超精密加工三维结构平台的性能研究,采用宏微双驱动协调控制,实现大行程和小步距的有机结合,对微动精密工作台性能进行实验,得到了平台运行的特性曲线。结果表明该机构的动态性和稳态性能良好,实现超低速、响应快、超高分辨率、高精度的双向步进运动,可以达到亚微米至纳米量级的定位精度,满足极微细电火花加工的高精度要求,为进一步研究压电陶瓷电机在超精密运动系统的应用、提高系统的定位精度,提供科学依据。     

压电陶瓷电机驱动的三维微动定位平台及验证

压电陶瓷电机具有高分辨率和压电驱动装置的动态特性,具有体积小、结构紧凑、成本低、输出力大、响应快、精度高、无电磁干扰等特点,但存在滞后误差、垂向位移误差,行程短的问题,尤其在电极损耗后,补偿量增大,严重影响了定位精度和难以满足三维加工的工作要求。该文通过对压电陶瓷电机驱动的百毫米以上超精密加工三维结构平台的性能研究,采用宏微双驱动协调控制,实现大行程和小步距的有机结合,对微动精密工作台性能进行实验,得到了平台运行的特性曲线。结果表明该机构的动态性和稳态性能良好,实现超低速、响应快、超高分辨率、高精度的双向步进运动,可以达到亚微米至纳米量级的定位精度,满足极微细电火花加工的高精度要求,为进一步研究压电陶瓷电机在超精密运动系统的应用、提高系统的定位精度,提供科学依据。     

掩模移动曝光系统精密定位工件台研制

为满足掩模移动曝光技术制作微光学元件的要求,研制了接近式曝光系统中使用的x-y二维精密移动工件台.该工件台由x-y二维整体手动工作台子系统、x-y二维掩模精密移动台子系统和承片台子系统组成.利用一个方导轨和两对V形导轨组成的滚动导轨副实现了x向和y向精密移动的导向功能;利用驱动器、电机、光栅、细分卡、单片机构成的闭环控制系统保证了x和y向的运动精度;在气浮的作用下,利用掩模版靠平基片实现了调平功能;利用差动螺旋机构和1∶2杠杆缩小机构实现了间隙的调整功能.经检测,工件台在8 mm的工作行程范围内,沿x,y方向移动的直线性分别达到了4"和3",两个方向的正交性达到了10",运动定位精度达到了1.2 μm.     

压电尺蠖直线电机的设计

为实现大行程、高分辨率精密驱动,该文提出了一种压电尺蠖直线电机的设计方法。首先,基于尺蠖运动原理,对电机进行了结构设计,它包括左、右箝位机构、驱动机构和输出轴,左、右箝位机构结构相同,用来对输出轴交替箝位与释放,驱动机构可以微米级及纳米级地步进输出位移,在左、右箝位机构及驱动机构的共同作用下,输出轴可连续输出大行程直线位移,该电机结构简单紧凑,便于调节,并可断电自锁;其次,采用有限元法对箝位机构及驱动机构进行了仿真分析,初步获得了电机的静、动态特性;最后,基于所搭建的实验系统,对电机的静、动态特性进行了测试。结果表明,在5mm的运动范围内,电机输出位移具有良好的直线性;在50 Hz的驱动电压作用下,电机运动速度为59.1μm/s;电机输出位移具有较高的分辨率,达到21nm。     

Design and performance of a dual drive system for tip-tilt angular control of a 300 mm diameter mirror

This paper presents the design, manufacture, and implementation of a dual-stage tip-tilt steering mechanism driven by ultra-high strain piezoelectric stacked actuators for coarse and fine motion control. The design of motion control systems often requires a compromise between range and bandwidth response. Consequently, for a given dynamic response, as range increases so too will following errors If advanced information is available, these errors may often be minimized by using feedforward techniques. In recent years, dual-stage systems which incorporate serially connected fine and coarse stages have demonstrated promising results. Related efforts (employing dual-stage methods) have addressed variants on designs using PZT elements, voice coils, or linear motors. The dual-stage uses a fine motion platform (with high frequency response and short range) to actively reduce following errors of the coarse platform which has a lower bandwidth response. This paper presents a dual-stage (also referred to as a multi-coaxial) tip-tilt mechanism with 6 degree of freedom (DOF) comprising two 3 DOF stages connected in series. The ultimate purpose of the mechanism is to position a 300 mm diameter mirror, hence it is referred to as a fast steering mirror. Also described is the nested control algorithm that is used to derive the drive signals for both the fine and coarse platforms. The algorithm provides a method by which the fine platform is actively driven to a commanded offset (usually its mid-range setting) by the coarse platform. Concurrently, the fine platform actively responds to the demand to reduce rapidly changing following errors. Finally, an experimental program is overviewed to assess the closed loop response for the fine, coarse, and dual-stage controllers. In one experiment, a sinusoidal input of amplitude ±300 μrad was employed at 10 Hz. The coarse controller generated a following error up to ±100 μrad at 10 Hz. In contrast, the dual-stage mechanism equipping both the coarse and fine controller reduced the following error to ±5 μrad. Frequency response plots of the closed loop control system are also presented and, with further optimization, indicate potential bandwidth improvements with small following errors and minimal phase lags up to 70 Hz.     

Technology 1992-industrial electronics

Important trends and events are highlighted. The use of fuzzy logic expanded. The use of programmable logic controllers in distributed control made headway. Low-cost vision systems were introduced, as were faster X-ray laminography systems. Growing emphasis on keeping humans who work around robots safe was evident. More robust motion and speed controls for both robots and motors became available     

Development of two-axis arm motion generator using active impedance

In this research a two-dimensional arm motion generator, composed of two linear motors, was developed. The inertia, damping and/or stiffness characteristics of the motion generator can be changed on the real-time basis by properly regulating the force generated by the linear motors. That is, active impedance is implemented without actual change in the physical structure of the motion generator. Control of the motor force is carried out by regulating the input currents supplied to the linear motors by using a common voltage-driven driver. In the control system, the time delay due to A/D conversion of the current output has an adverse effect on the stability of the system. Furthermore, disturbances caused by characteristics of the motion generator also exist. To cope with these difficulties, a 2-DOF controller combined with LQ-servo and H-infinity controllers was used. The gains of the controller are selected so that disturbance rejection, stability guarantee and tracking performance may be achieved. This motion generator can be used to measure kinesthetic sense associated with the human arm and thus leads to developing the products for which the kinesthetic sense is taken into account.     

Nonlinear control of mechatronic systems with permanent-magnet DC motors

The current trends in development and deployment of advanced electromechanical systems have facilitated the unified activities in the analysis and design of state-of-the-art motion devices, electric motors, power electronics, and digital controllers. This paper attacks the motion control problem (stabilization, tracking, and disturbance attenuation) for mechatronic systems which include permanent-magnet DC motors, power circuity, and motion controllers. By using an explicit representation of nonlinear dynamics of motors and switching converters, we approach and solve analysis and control problems to ensure a spectrum of performance objectives imposed on advanced mechatronic systems. The maximum allowable magnitude of the applied armature voltage is rated, the currents are limited, and there exist the lower and upper limits of the duty ratio of converters. To approach design tradeoffs and analyze performance (accuracy, settling time, overshoot, stability margins, and other quantities), the imposed constraints, model nonlinearities, and parameter variations are thoroughly studied in this paper. Our goal is to attain the specified characteristics and avoid deficiencies associated with linear formulation. To solve these problems, an innovative controller is synthesized to ensure performance improvements, robust tracking, and disturbance rejection. One cannot neglect constraints, and a bounded control law is designed to improve performance and guarantee robust stability. The offered approach uses a complete nonlinear mechatronic system dynamics with parameter variations, and this avenue allows one to avoid the conservative results associated with linear concept when mechatronic system dynamics is mapped by a linear constant-coefficient differential equation. To illustrate the reported framework and to validate the controller, analytical and experimental results are presented and discussed. In particular, comprehensive analysis and design with experimental verification are performed for an electric drive. A nonlinear bounded controller is designed, implemented, and experimentally tested.     

New design of hybrid-type self-bearing motor for small, high-speed spindle

A new structure of hybrid (HB)-type self-bearing motor is proposed for miniature spindle motors. The proposed design combines the HB-type self-bearing motor and HB active magnetic bearing in the common stator and rotor pair to generate large radial forces. First, the principle and theoretical background are introduced. Then, the air gap flux is analyzed by the finite element method, and radial forces for the proposed and standard-type HB self-bearing motors are compared. Finally, experiments are conducted to confirm the performance of the proposed motor. The motor can run at relatively high rotating speed with relatively high torque compared with its small size. The levitation is very stable and the motor indicates good performance for practical application.     

美国MicroE圆光栅在数控转台和DDR电机领域的应用及特点

近年来,对精确自动测量转角的要求大大增长,作为自动测量仪器和装备的关键元件圆光栅及反馈系统的需求也日趋迫切。很多部门在精密加工、精密测量和自动控制等方面,使用圆光栅就可以实现自动测量、数显和数控。     

Adaptive robust motion control of SISO nonlinear systems with implementation on linear motors

For the purpose of controlling an X–Y table driven by linear motors with a high precision, an adaptive robust motion tracking control method is first introduced. The controller is developed based upon a class of SISO nonlinear systems whose nonlinear part can be linearly parameterized. The advantage of such a controller is that parametric uncertainties and unknown disturbances can be dealt with, which is essential for a high precision of the control of linear-motor-driven X–Y table. With the prior knowledge of the bounds of the system parameters, a discontinuous projection is utilized in the adaptive law to ensure the boundedness of the parameters estimates. The algorithm is then implemented on a real X–Y table driven by the linear motors. In the modeling of such a system, fiction effects are also considered, which is useful for the derivation of the adaptive law. Experiments on the X–Y table are carried out and the results show excellent tracking performance of the system.     

Optimal Synchronization Control of High-Precision Motion Systems

Recently, in the motion control area, one of the most challenging problems has been synchronization control of multiple motion axes or drivers. Unfortunately, the majority of the previous approaches have not fully addressed the synchronization problem when the system performs a complex motion. In this paper, a novel synchronized design of the high-precision motion control system is presented. The basic idea is to introduce the coupling and synchronization factors into the definition of the synchronization error. Then, a new quadratic performance index incorporating the synchronization errors of the multiple motion axes is introduced so that the resulting control law generates the cross-coupling control action, and as a consequence, improved tracking and synchronization performance can be obtained. The key to the success of the new design is to ensure that each motor tracks its desired trajectory while synchronizing motion with others. Computer simulations and real-time experiments on a servo system with two permanent-magnet linear motors demonstrate the effectiveness of the method.     

IC加工及检测装备超精密工作台自标定技术研究

在对超精密工作台自标定相关文献综述的基础上,基于刚体运动方程和非线性最优化方法,提出了一种超精密工作台自标定算法。仿真结果表明:该算法可以实现超精密工作台的标定,并且其最终标定精度与辅助测量装置精度无关,只受自标定过程中随机测量噪声的影响。     

Robust Fuzzy Neural Network Sliding-Mode Control for Two-Axis Motion Control System

A robust fuzzy neural network (RFNN) sliding-mode control based on computed torque control design for a two-axis motion control system is proposed in this paper. The two-axis motion control system is an$x-y$table composed of two permanent-magnet linear synchronous motors. First, a single-axis motion dynamics with the introduction of a lumped uncertainty including cross-coupled interference between the two-axis mechanism is derived. Then, to improve the control performance in reference contours tracking, the RFNN sliding-mode control system is proposed to effectively approximate the equivalent control of the sliding-mode control method. Moreover, the motions at$x$-axis and$y$-axis are controlled separately. Using the proposed control, the motion tracking performance is significantly improved, and robustness to parameter variations, external disturbances, cross-coupled interference, and friction force can be obtained as well. Furthermore, the proposed control algorithms are implemented in a TMS320C32 DSP-based control computer. From the simulated and experimental results due to circle and four leaves reference contours, the dynamic behaviors of the proposed control systems are robust with regard to uncertainties.