非共振型压电电机驱动的大行程精密定位旋转平台的建模和实验

针对目前光波导封装使用的精密定位平台行程小,结构与控制系统复杂的问题,提出了非共振型压电电机驱动的大行程精密旋转定位平台。该平台通过压电电机的连续作动和步进作动两种工作模式来满足大行程和高精度要求。首先对该精密旋转定位平台进行动力学建模,确定了系统运动方程。然后,分析其作动机理,研究影响旋转平台转速的不同因素。最后,实验研究该精密旋转定位平台的速度、步距、分辨率与负载特性,确定平台连续作动与步进作动的驱动方式。实验结果表明,在直流偏置为60V,峰峰电压为120V,频率为180 Hz的正弦波电压激励下,该精密旋转定位平台最大转速可达47 963.2μrad/s,分辨率和最大负载分别为3μrad和60g。与现有的大行程精密定位旋转平台相比,设计的平台具有行程大,精度高,结构简单,稳定可控,且装配调试方便,易于批量化生产等优势。     

Development of a “walking drive” ultraprecision positioner

The present paper presents a new mechanism to feed a precision table continuously over a long stroke with high rigidity by utilizing deformations of piezoelectric actuators. A driving method names “walking drive” is employed for the mechanism with which the table is driven in a similar way to the walking motions in animals. A precision feed device is developed, and ultraprecision positioning experiments are carried out by using the device combined with a laser-feedback system developed. It is confirmed that the positioner driven by the walking drive has the following advantages: (1) positioning resolution of 5 nm is realized with a simple control method and a simple mechanism, because of no friction against the feed motion; (2) smooth continuous path control with the following error of less than 10 nm is realized over a long stroke despite short strokes of the piezoelectric actuators; and (3) high stiffness of greater than 350 N/μm is realized in the feed direction.     

Flexural-hinge guided motion nanopositioner stage for precision machining: finite element simulations

Finite element analysis has been used to study the behavior of flexural-hinge guided- motion nanopositioning stages designed for use in precision machining. The primary criteria of such nanopositioners are a high stiffness and large load carrying ability. Both static loading and modal frequency analysis are performed. A procedure is developed by which we can redesign and reanalyze the model while simulating the performance of the nanopositioner. Modification of dimensions enables us to control and optimize resonant frequency, displacement, stresses, and force to be applied to the hinges to achieve the desired response of the positioner and the positioner motion.     

压电驱动柔性铰链机构传动实现超精密定位

简单介绍压电元件和柔性铰链的概念与特点。列举压电元件与柔性铰链机构结构实现超精密定位的典型例子，包括超精密测量、超精密加工、光学自动聚焦和大行程超精密定位。为使超精密定位工作台的结构紧凑，提出单驱动多自由度运动机构。应用蠕动式的运动原理可合成机构上的多自由度运动，并实现大行程运动。设计了对称结构的柔性铰链机构实现导向功能。制造和装配了微小型平面工作台。     

Design and precision construction of novel magnetic-levitation-based multi-axis nanoscale positioning systems

This paper presents two novel six-axis magnetic-levitation (maglev) stages capable of nanoscale positioning. These stages have very simple and compact structures, which is advantageous to meet the demanding positioning requirements of next-generation nanomanipulation and nanomanufacturing. Six-axis motion generation is accomplished by the minimum number of actuators and sensors. The first-generation maglev stage, namely the Δ-stage, is capable of generating translation of 300 μm and demonstrates position resolution better than 2 nm root-mean-square (rms). The second-generation maglev stage, namely the Y-stage, is capable of positioning at a resolution better than 3 nm rms over a planar travel range of 5 mm × 5 mm. A novel actuation scheme was developed for the compact structure of this stage that enables six-axis force generation with just three permanent-magnet pieces. This paper focuses on the design and precision construction of the actuator units, the moving platens, and the stationary base plates. The performance of the two precision positioners is compared in terms of their positioning and load-carrying capabilities and ease of manufacture. Control system design for the two positioners is discussed and an experimental plant transfer function model is presented for the Y-stage. The superiority of the developed instruments is also demonstrated over other prevailing precision positioning systems in terms of the travel range, resolution, and dynamic range. The potential applications of the maglev positioners include semiconductor manufacturing, microfabrication and assembly, nanoscale profiling, and nanoindentation.     

高精密滚转角测量干涉仪

现有的各种激光干涉仪可以方便地测量围绕垂直于直线位移方向的两个转角偏移,但是对于围绕运动轴的滚转角偏移,特别是对于大行程运动,缺乏有效的测量方法。针对各种高精密直线运动定位装置,设计一个新型的差分平面干涉仪,并采用一个楔面棱镜和楔面反射镜,组合成为一个几何空间对称四光路系统,构成新型的高精密滚转角激光干涉测量仪。它不需要与行程同长的大反射参考镜,但同样能实现高分辨率,而且简便实用,可以直接溯源米定义。试验证明,几何空间对称四光路滚转角干涉测量仪能够有效地排除其他自由度运动的干扰,利用它可以快速高效地测量各种精密直线位移运动的滚转角。使用普通的2π/360细分相位计,测量分辨率为1.1″,若使用2π/36 000的高精密细分相位计,滚转角的测量分辨率可达到0.01″。     

一种高分辨率的光纤定位单元定位精度的测量装置

目前对光纤定位单元定位精度的检测所使用的测量手段是摄影测量,由于被测光纤的孔径非常小,使得这种测量方法的分辨率不高。该文提出了一种新的测量方法,检测装置由显微镜、CCD相机、二维精密移动平台组成。被测光纤通过显微镜放大成像于CCD中,通过对CCD所拍摄照片的实时处理,建立位置反馈机制,实时操控二维精密移动平台追随光纤运动,光纤在运动中始终成像于CCD视场中心,通过读取移动平台坐标的变化来表征光纤移动的位置变化。实验结果表明,该套测量系统的分辨率达到了0．1μm,重复定位精度1．5μm,实现了高精度的检测要求。     

Computational parametric analysis and experimental investigations of a compact flexure-based microgripper

This paper presents a flexure-based piezoelectric actuated microgripper for high precision grasping/releasing tasks. The design of the microgripper consists of a three-stage amplification and transmission mechanism, and the parallel grasping technique. A bridge-type mechanism and two sequential lever-type mechanisms are symmetrically connected to amplify the output displacement of the embedded piezoelectric actuator. The parallelogram mechanisms assist in linearizing the output displacement of both jaws of the microgripper. The computational analysis is conducted to investigate the effect of the dimensional parameters on the characteristics of the microgripper. A computational parametric optimization methodology is established to achieve the required attributes of the microgripper. The design optimization resulted in a compact design, a high displacement amplification ratio, and a large output displacement of the microgripper. The experimental studies are conducted to investigate the key characteristics of the microgripper such as the displacement amplification ratio, the output displacement, tracking performance. Further, the parasitic motion, input-end and output-end motion resolution of the microgripper are identified. The experimental results indicate that the compact microgripper can achieve a high displacement amplification ratio and large output displacement with a high positioning accuracy.     

LOADS INFLUENCE ANALYSIS ON NOVEL HIGH PRECISION FLEXURE PARALLEL POSITIONER

A large workspace flexure parallel positioner system is developed, which can attain sub-micron scale accuracy over cubic centimeter motion range for utilizing novel wide-range flexure hinges instead of the conventional mechanism joints. Flexure hinges eliminate backlash and friction, but on the other hand their deformation caused by initial loads influences the positioning accuracy greatly, so discussions about loads' influence analysis on this flexure parallel positioner is very necessary. The stiffness model of the whole mechanism is presented via stiffness assembly method based on the stiffness model of individual flexure hinge. And the analysis results are validated by the finite element analysis (FEA) simulation and experiment tests, which provide essential data to the practical application of this positioner system.     

Robust control of XYZ flexure-based micromanipulator with large motion

This article describes the development of an XYZ flexure-based micromanipulator, with the features of decoupled kinematic structure, large motion range, high positioning precision, and fast response. The large motion range of flexure mechanisms is quantified by a given definition. Based on the given definition, large motion is achieved in the mechanical design of the XYZ-flexure parallel mechanism (FPM). To ensure high positioning precision and fast dynamic response, a hybrid control algorithm with both position control and vibration control are designed, using the H_∞-theory. The controller strongly solves the three common problems of flexure mechanisms simultaneously, including unmodeled uncertainties, the external disturbances and vibration caused by inherent low damping.     

Design of a precision multi-layer roll-to-roll printing system

Roll-to-roll (R2R) printing technologies have been widely adopted in a variety of engineering fields, e.g., organic photovoltaics and flexible electronics, owing to the advantages of cost and throughput. Although a minimum feature size of 100 nm has been demonstrated on R2R systems, the layer to layer registration accuracy (i.e., overlay accuracy) still remains as low as tens of microns, which prevents the fabrication of common electronic and functional devices, such as transistors. To realize the full potential of R2R technologies, the registration accuracy must be improved to match the printing resolution, i.e., 100s nm. To address the issue, we have developed a multi-layer R2R system with multiple-input multiple-output (MIMO) closed-loop control that achieves submicron level alignment precision for large-scale continuous printing processes. The enabling elements in the multi-layer R2R system include: (1) new vision-based alignment algorithm/method, which provides 100s nm position detection capability based on low-cost cameras; and (2) custom-built five-axis compliant roller positioner. Experimental results show that the compliant roller positioner has a ±1 mm range with 100s nm precision in X, Y, and Z axes respectively. For correcting in-plane web errors, the roller positioner can achieve a range of 1 mm with < 1 μm precision, realizing multi-layer R2R printing with submicron overlay accuracy. Based on the new methods, a gate/source-drain multi-layer electrode structure for field-effect transistors (FETs) has been designed and fabricated on a 4-inch PET web, demonstrating better than 1 μm overlay precision in fabricating flexible electronics on a R2R platform for the first time.     

光电探测系统辅助SINS的动态对准方法

针对陆地战车对定位和定向系统的要求越来越高,提出了一种高精度的对准方法。采用光电探测系统计算出精确的车辆位置和航向,在两次光学定位过程中利用运动约束与零速修正组合的方法估计出惯导系统系统误差,进而估算出光电探测系统与捷联惯导系统之间的敏感轴安装偏角。仿真结果表明:光电探测系统的定向精度优于10″,定位精度优于0.1 m,敏感轴安装偏角的估计精度优于20″,因此本系统满足陆用战车的高精度动态对准需求。     

Large stroke and high precision positioning using iron–gallium alloy (Galfenol) based multi-DOF impact drive mechanism

A miniature-positioning device with a large stroke motion has attracted more and more attentions in these years because of the intensive development in precision engineering. In this paper, we have achieved the large stroke actuating and the high precision positioning, as well as realized a multi-degree-of-freedom in-plane motion using the developed Galfenol impact drive mechanism (IDM) actuator. In order to enhance the system robustness, two pieces of U-shape Galfenol (iron–gallium alloy) have been employed as the driving elements with a bias magnetic field contributed by a permanent magnet to generate the swing motion that amplifies the propelling inertia force. The current amplitude modulation has been applied in the precision positioning of the actuator under the quasi-static condition because of the motion step-size fineness. The results show that the actuator is able to achieve a sub-micrometer positioning accuracy that has reached the measurement limit of our setup. Meanwhile, the frequency modulation method has been explored in the large stroke actuation with a high motion speed. We have found out that this design is capable of achieving an accurate positioning without the frequency modulation because of the intrinsic fine step-size of the actuator. In addition, a rectangular in-plane motion has been realized with the image-based control for the multi-degree-of-freedom positioning. The actuator has an inductive impedance with a resistance of 3.796 Ω and an inductance of 0.4697 mH. Under the present driving ratings, the power consumption is smaller than 1.97 W while the reactive power can be ignored. Moreover, the experimental load analysis indicates that the design can achieve a maximum carry-load-to-weight ratio of 6.5.     

机器人恒压球形公自转磨头抛光技术研究

采用工业机器人进行大口径光学元件的研抛过程中,机器人自身定位误差会导致研抛压力产生波动,进而影响去除函数稳定性,为此提出了一种机器人恒压球形公自转磨头抛光方法,并对其结构、工作原理、机器人定位特性以及研抛压力输出特性开展了研究。首先,基于Preston理论构建了材料去除模型,对去除函数形状进行了分析,对所设计抛光磨头的机械结构与工作原理进行了介绍。然后,对机器人定位误差以及磨头输出力响应性与稳定性进行了测量,验证了所提方法能够较好地适应机器人研抛压力波动而做出的力响应控制。最后,进行了定点抛光以及粗、精磨抛加工实验。实验结果表明：利用所提方法去除函数的稳定性强,通过10个周期的粗、精抛加工,面形收敛率分别为9095%、7261%,可获得较高的加工精度与面形质量。     

杠杆式尺蠖压电直线驱动器

设计了一种基于尺蠖运动原理的压电直线驱动器,用于解决光学领域中的精密定位问题。该驱动器采用了对称杠杆式位移放大机构,在保证钳紧力的同时,可以获得较大的驱动位移。阐述了尺蠖式压电驱动器的工作原理,对杠杆式柔性放大机构的位移损失、压电陶瓷与柔性机构的耦合特性及箝位机构与中间驱动机构的刚度进行了分析。利用有限元软件Ansys对钳位机构和驱动机构的变形、应力、输出位移和固有频率等参数进行了仿真分析。最后,搭建了实验平台,测试了驱动器的各项性能。测试结果显示,该驱动器的行程为±25mm,钳紧力为17N,承载力为11N,最大和最小步距分别为55μm和60nm。当驱动电压为150V时,驱动器的最高驱动速度为1.259mm/s。得到的性能指标满足光学领域精密定位需要。     

Design and performance evaluation of a 3-DOF mobile microrobot for micromanipulation

In this paper, a compact 3-DOF mobile microrobot with sub-micron resolution is presented. It has many outstanding features: it is as small as a coin ; its precision is of sub-micrometer resolution on the plane; it has an unlimited travel range; and it has simple and compact mechanisms and structures which can be realized at low cost. With the impact actuating mechanism, this system enable both fast coarse motion and highly precise fine motion with a pulse wave input voltage controlled. The 1-DOF impact actuating mechanism is modeled by taking into consideration the friction between the piezoelectric actuator and base. This modeling technique is extended to simulate the motion of the 3-DOF mobile robot. In addition, experiments are conducted to verify that the simulations accurately represent the real system. The modeling and simulation results will be used to design the model-based controller for the target system. The developed system can be used as a robotic positioning device in the micromanipulation system that determines the position of micro-sized components or particles in a small space, or assemble them in the mesoscale structure.     

基于磁杆直线电机的光学延迟线研究

在太赫兹时域波谱系统中,通过光学延迟线的时间延迟实现对太赫兹时域信号的采集,而传统的光学延迟线存在扫描速度慢、光学延迟分辨率低等问题。为此,提出了一种采用磁杆直线电机作为驱动和传动一体装置,并加入光栅测量系统的光学延迟线改进方案。测试结果表明,该方案可实现长距离内高速、精准往复运动,同时提供高达512 ps的延时范围和0.033 fs(位置定位精度0.01μm)的光学延迟分辨率,显著提高了太赫兹时域波形振幅的稳定性。     

Robust control of XYZ flexure-based micromanipulator with large motion

This article describes the development of an XYZ flexure-based micromanipulator, with the features of decoupled kinematic structure, large motion range, high positioning precision, and fast response. The large motion range of flexure mechanisms is quantified by a given definition. Based on the given definition, large motion is achieved in the mechanical design of the XYZ-flexure parallel mechanism (FPM). To ensure high positioning precision and fast dynamic response, a hybrid control algorithm with both position control and vibration control are designed, using the H_∞-theory. The controller strongly solves the three common problems of flexure mechanisms simultaneously, including unmodeled uncertainties, the external disturbances and vibration caused by inherent low damping.     

Development of a linear electrostrictive servo motor

This paper presents a linear electrostrictive servo motor with high resolution and large stroke for ultra-precision motion control. High thrust force is obtained by making use of an electromagnetic clamping mechanism with force magnifying structure in the motor design. An operator alterable iterative learning control algorithm is proposed for the motion control of the motor. A prototype is designed, fabricated and tested. Experimental results show that the prototype has a mechanical resolution of 0.02 μm, yaw error less than 2 μm and maximum thrust force of 30N. Applications of the motor include producing the servo feed motions required in micro electrical discharge machining (micro-EDM) system or as a motion control device for other precision machining systems.