浅谈角度编码器的精度

几乎每个设备都含有编码器,许多自动化系统依赖精密旋转运动;旋转式计算机直接制板机(CTP)、机器A、B及C轴、表面贴装机、形状测量、晶片处理和检测以及测角仪都使用某种形式的旋转式或角度编码器.     

高精度绝对式编码器的研发与应用

一、概述随着我国机床、伺服电机行业的迅速发展,对伺服电机的转速、精度及功能作用的要求越来越高,而伺服电机的这些功能主要取决于编码器的精度,需要编码器有更高的采样精度和数据位数。由于绝对值编码器在编码器内部所有位S值在编码生成后,其堡程内所有的位置均有一一对应的代码(二进制、BCD代码)输出。     

Development of a three-degree-of-freedom laser linear encoder for error measurement of a high precision stage

In this study, a laser linear encoder with three degrees of freedom (3-DOFs) based on diffraction and interference was developed to measure the linear displacement and two angular errors of a linear moving stage. Parts of the linear motion errors induced from the two angular errors can be calculated by this prototype 3-DOF laser encoder. It was an effective method for online error calculation and compensation to improve precision stage performance. This new function was superior to other laser encoders. The verification results showed that the resolution is 20 nm. It detected displacements relative to an external grating scale with accuracy of about +/-150 nm for a measuring range of +/-1 mm, and detected the angular errors with related accuracy of about +/-1 arc sec for a measuring range of +/-100 arc sec.     

Note: Development of a high resolution six-degrees-of-freedom optical vibrometer for precision stage

A high resolution six degrees of freedom (6-DOF) optical vibrometer is proposed. 6-DOF vibrations can be simultaneously measured using the proposed optical vibrometer, which reduces measurement time and number. The performance of the proposed vibrometer is verified by experiments. The results show that the accuracy of the proposed optical vibrometer is ±30 nm∕200 nm and ±0.04 arcsec∕0.1 arcsec at 1000 Hz.     

应用超声电机的多关节机器人的设计与分析

主要设计了一个由超声电机驱动多关节机器人手臂。这种电机单位质量的转矩高,在低速下有大转矩输出,且不产生电磁干扰。利用ADAM S软件平台模拟机构的运动学和动力学,整体性能预测,结构模型优化,利用仿真结果重新设计手臂结构,为物理样机设计制造提供依据。     

Comparison of angle standards with the aid of a high-resolution angle encoder

Germany's National Metrology Institute the Physikalisch-Technische Bundesanstalt (PTB) and the DR. JOHANNES HEIDENHAIN GmbH (HEIDENHAIN) have conducted and compared measurements using their primary angle standards, which are realized as angle comparators of similar design. A high-resolution digital angle encoder served as the transfer standard for this comparison. Calibrations of the transfer standard by the two angle comparators resulted in an agreement of ±0.002″. The result proved to be consistent with the measurement uncertainties that the participants attributed to their calibration. PTB succeeded, using an additional comparison with a self-calibration method, in improving the measurement uncertainty of its comparator by a factor of 2.5 to 0.002″ (k = 2). The results of both participants demonstrated the suitability of the digital angle encoder as transfer standard for angle measurement comparisons aimed at uncertainties of a few thousandths of an arcsecond.     

基于DSP的高精度函数信号发生器设计与实现

基于DSP的信号发生器因为其编程的高度灵活性,波形的高精度、高稳定性等特点,在雷达应用,通信系统的仿真与测试等国防、科研和工业领域具有很大的应用价值和应用前景.本文主要介绍基于TMS32OVC5402和DDS技术实现信号发生器的设计和实现方法.     

高精度超声波辅助珩齿装置设计

分析了超声波珩齿装置中轴承的径向误差造成的珩齿轮径向偏差的大小;列出了珩齿轮相对于被加工齿轮的几种偏差形式,并给出了这几种偏差造成被加工齿轮的径向误差、公法线长度的变化、接触线方向误差、齿轮螺旋线误差和齿的锥度误差的计算方法.     

Improving the performances of ultrasonic motors using intermittent contact scheme

Most ultrasonic motors operate in intermittent contact scheme. Their stators drive the rotors (or sliders) when the stators contact the rotors, and the rotors (or sliders) move under an inertia force when the stators and the rotors are separated. The duty cycle of the contact and the “flight” manages motors’ output performance. To obtain a large output force or output velocity, this paper proposes a concept using the alternative work of a multi-stator or the multi-driving end of a single stator. The method can avoid larger noise, poor efficiency, and lifetime of motors. A novel linear ultrasonic motor using the alternative work of the multi-driving end of a single stator was fabricated and investigated experimentally. The traveling speed without load of the slider is 88 mm/s, and the maximum load is 0.32 N.     

Improving the performances of ultrasonic motors using intermittent contact scheme

Most ultrasonic motors operate in intermittent contact scheme. Their stators drive the rotors (or sliders) when the stators contact the rotors, and the rotors (or sliders) move under an inertia force when the stators and the rotors are separated. The duty cycle of the contact and the “flight” manages motors’ output performance. To obtain a large output force or output velocity, this paper proposes a concept using the alternative work of a multistator or the multi-driving end of a single stator. The method can avoid larger noise, poor efficiency, and lifetime of motors. A novel linear ultrasonic motor using the alternative work of the multi-driving end of a single stator was fabricated and investigated experimentally. The traveling speed without load of the slider is 88 mm/s, and the maximum load is 0.32 N.     

高精度超声波式飞机油量传感器设计

运用超声波测距原理设计了超声波式飞机燃油油量传感器.该传感器具有体积小、重量轻和精度高等优点,可以准确地、实时地测量飞机各油箱的燃油油量,有助于实现飞机燃油系统的精确测控.     

大量程高精度三维姿态角测量系统设计

基于针孔成像和双矢量定姿原理,设计一种使用单图像传感器实现大量程高精度三维姿态角测量的方法.根据系统要求设计双基准平行光源,采用FPGA单芯片实时实现图像传感器的驱动成像、光斑的分割与质心定位及与USB之间的快速通信,通过光斑质心坐标计算得到双基准平行光源的方向矢量,根据双矢量定姿原理计算姿态敏感器的旋转矩阵,得到三维姿态角;根据针孔成像模型,建立姿态敏感器的内外参数统一标定模型,对测量系统进行标定,标定结果和测量实验表明,三维姿态角测量系统的视场范围达到19.6°×19.6°,俯仰角、偏航角、滚动角的精度达到9.9″、9.3″、80.2″.     

Modeling,analysis and suppression of current harmonics of Langevin-type ultrasonic motors under high voltage

For achieving high speed and large thrust, Langevin-type ultrasonic motors (LTUM) are generally operated under high voltage. However, high voltage causes the current harmonics of piezoelectric material nonlinear phenomena, which will decrease the efficiency, the output force, and the accuracy of LTUMs. In this study, the nonlinearity of current harmonics of LTUM are described and analyzed by a novel nonlinear equivalent circuit model using Lagrange equations. Thereafter, based on a nonlinear tuning method, a specific driver circuit is suggested to suppress the current harmonics. Experimental results validate that the time response of the current is consistent with that of the model and furtherly demonstrate that the total harmonic current distortion decreases by 68% utilizing the proposed nonlinear tuning method under 500 Vpp.     

脉冲编码器、测速发电机性能自动测试分析系统

脉冲编码器、测速发电机是传动系统中常用的速度传感器,其性能分坏直接影响控制系统的品质指标。本文设计实现了一种基于微机脉冲编码器,测速发电机性能自动测试系统,对该系统的硬件构成和软件分析功能进行了详细讨论。     

喷射式超声波发生器及应用

介绍了一种机械型超声波发生器,可用作二相以上液体的乳化,分散等工业上的混合作业。     

A high performance one-dimensional homodyne encoder and the proof of principle of a novel two-dimensional homodyne encoder

Displacement laser interferometers and interferometric encoders currently are the dominating solutions to the displacement measurement applications which require measurement uncertainties in the order of a few nanometers over hundreds of millimeters of measurement range. But, in comparison with interferometric encoders, to achieve nanometer order or even lower measurement uncertainties, displacement laser interferometers require much stricter environmental control if not vacuum, which will increase their Total Cost of Ownership (TCO). Therefore interferometric encoders are getting more and more preferable. Furthermore, for some applications, the measurement of the out-of-plane displacement is required as well. Therefore, in this work, a one-dimensional interferometric encoder was built and investigated, a novel two-dimensional (one is in-plane, the other one is out-of-plane) interferometric encoder was devised and its principle was proven experimentally. For the one-dimensional encoder, a periodic nonlinearity of ±50 pm with HEIDENHAIN EIB 741 and a periodic nonlinearity of less than ±10 pm with a home built phase meter and off-line Heydemann correction were identified through a comparison measurement with a differential heterodyne interferometer. In addition, this one-dimensional encoder was identified to have a better measurement stability compared to the differential heterodyne interferometer.     

Velocity vector profile measurement using multiple ultrasonic transducers

This paper proposes a new technique that enables the measurement of the velocity vector in multi-dimensions on a line of the flow field. A system to achieve this goal was developed based on the ultrasonic velocity profiling by using multiple transducers. A two-dimensional system was constructed and successfully applied to an actual flow field for two-dimensional velocity vector measurements. To estimate the influence of the existence of a wall, acoustic field under the developed system was calculated by solving two-dimensional wave equation and then the focal point of an ultrasonic beam was determined to optimize the system. The system was applied to measure the two-directional velocity components of a periodic velocity fluctuation in the wake of a cylinder as an example of unsteady flow. Temporal variation of velocity vector profiles well represent the velocity fluctuation, and vorticity distribution, which is obtained from the spatial distribution of velocity vector, well represents the vertical motion in the wake.     

Design and development of a high precision lens focusing mechanism using flexure bearings

The emergence of multi-tier stacked die architecture in semiconductor devices has given rise to the need for multi-level interconnection between dies (bare IC chips) and the substrate. In the context of interconnection by wire bonding, this necessitates the use of a vision system, which has real time focussing capability. This paper presents the design and development of such a high precision programmable focussing mechanism (PFM), which is used to move a lens relative to another fixed lens, thus altering the focus of the optical system. The device employs flexure bearings and is actuated by a voice coil motor (VCM).     

Note: Vector network analyzer-ferromagnetic resonance spectrometer using high Q-factor cavity

A ferromagnetic resonance (FMR) spectrometer whose main components consist of an X-band resonator and a vector network analyzer (VNA) was developed. This spectrometer takes advantage of a high Q-factor (9600) cavity and state-of-the-art VNA. Accordingly, field modulation lock-in technique for signal to noise ratio (SNR) enhancement is no longer necessary, and FMR absorption can therefore be extracted directly. Its derivative for the ascertainment of full width at half maximum height of FMR peak can be found by taking the differentiation of original data. This system was characterized with different thicknesses of permalloy (Py) films and its multilayer, and found that the SNR of 5 nm Py on glass was better than 50, and did not have significant reduction even at low microwave excitation power (-20 dBm), and at low Q-factor (3000). The FMR other than X-band can also be examined in the same manner by using a suitable band cavity within the frequency range of VNA.     

基于双光栅尺的高速高精度位移测量方法

提出了一种基于双光栅尺的高速高精度位移测量方法。在分析光栅尺测量原理的基础上,探讨双光栅尺信号的切换合成;通过对莫尔条纹电子细分计数脉冲切换误差的分析,研究减小切换合成误差的方法;采用可编程逻辑器件FPGA设计信号处理电路,并通过逻辑、时序仿真,验证了本方法的可行性。实验结果表明:此方法在光栅尺移动速度＞1 m/s时,具有10 nm分辨率,可满足新一代运动定位系统对高速高精度位移测量的要求。