磁浮列车磁场测量系统中运动控制平台的设计

磁浮列车气隙磁场的测量可以为列车电磁系统的设计和控制提供重要依据．本文对气隙测量系统中磁传感器运动控制平台的设计进行了详细介绍,阐述了运动控制平台的工作原理和光栅尺信号的处理方法．采用双计数器鉴相法消除了光栅尺抖动的影响,提高了传感器的定位精度．同时采用电流矢量恒幅旋转的细分方法实现了步进电机恒转矩均匀细分控制,提高了步进电机的分辨率和运行稳定性．所设计的运动控制平台的定位精度可以达到1μm．     

一种简易结构步进分幅式航空相机摆扫控制系统

步进分幅式成像是提高传统面阵CCD 航空相机工作覆盖范围的重要方法.本文介绍了一种简易结构的步进分幅式航空相机.相机采用步进电机开环控制实现摆扫过程,适用于对体积和重量要求严格的场合.文中着重介绍了一种基于正矢函数的高阶平滑步进电机运动曲线的设计及其在DSP 平台上的实现方法.实验表明,该运动控制方式有效地抑制了冲击和振动,避免了步进电机的丢步,重复性定位精度优于10″.系统结构简单,成本低,满足分幅式航空相机的要求.     

二维精密定位平台控制算法研究

本文设计了一种二维平台自动定位系统及控制方案,该系统利用光栅位移传感器的光电转换原理产生平台位置信息,利用电机驱动器控制电机旋转.光栅尺数显表和电机驱动器通过串口与计算机相连,计算机利用LabVIEW软件编写控制程序并控制平台移动,然后把平台的位置变化实时显示出来并保存相关数据,最后使用MATLAB软件对位置数据进行分析、处理.该系统使用位置式PID、速度积分式PID以及模糊控制技术分别对二维平台进行自动定位控制,最后通过稳定时间及稳定精度的比较,选择最适合的速度积分式PID控制技术作为本系统最终采用控制方案.实验结果证明,本文所设计的定位系统实时性高,定位精度可达微米级.     

基于CPLD的带细分的三相步进电机驱动器设计

混合式步进电机的工作原理类似于永磁同步电机,完全可以引入同步电机的先进控制方法.从同步电机控制的角度来控制步进电机,就从根本上跳出了步进电机细分控制是对相电流控制的限制,实现了全新的脉冲细分控制。基于这一理论开发出以CLPD为核心的三相混合式步进电机脉冲细分控制器。     

步进电机细分及其在光电测径系统中的应用

叙述了步进电机的细分技术及其测长原理。作为一种测长手段应用于工件直径测量系统中，为提高步进电机细分测长的精度，系统采用了软件补偿的办法，应用光电定位和ＭＣＳ—５１单片机实施控制，构成一种测量范围在１～１００ｍｍ，精度较高，效费比高的光电测径系统。     

应变仪自动校准装置的研制

应变仪是一种广泛应用于工程质量监测的重要传感器，主要用于大坝、桥梁等各种结构的应变测量。本文针对当前应变仪自动校准的实际需求，设计了一种基于高精度滚珠丝杠机构、检测平台、高精度光栅位移传感器、步进电机、数据采集卡和工控机的自动校准系统。通过计算机录入设定的一系列需要校准的应变数值，由此计算得到控制步进电机的脉冲数，计算机通过数据采集卡控制步进电机带动滚珠丝杆机构运动，同时检测平台和光栅位移传感器一起平动，光栅位移传感器将平台位置以脉冲的形式通过数据采集卡发送到计算机，从而实现应变的高精度闭环控制，再由软件分析得到标定方程与误差。该系统可以实现测量范围0～300mm的高精度校准，其中校准精度可达到10μm，核定负载能达到60kg，特别适用于计量检测等单位中应变仪的校准。     

基于CPLD和MCU的光轨闭环控制系统设计

标准光源在光轨上的精确定位是光学测量系统的重要组成部分,执行机构需要运行平稳、噪音低、定位精度高.根据系统要求,设计实现了基于CPLD和MCU的位置闭环控制系统.系统以CPLD作为光栅信号采集、步进电机变频输出等辅助数字系统,在MCU控制和处理下,实现了由光栅反馈信息,经模糊算法、变频处理后驱动步进电机的全闭环跟踪过程,同时系统还设计有与上位机数据交换和无线遥控等功能.实践表明:系统震动小、噪音低、运行平稳、定位精度高,采用栅距0.05mm的光栅,其重复定位不确定度≤0.1mm.     

磁致伸缩液位计测量装置的研制

针对磁致伸缩液位计的量值溯源问题,研制了磁致伸缩液位计测量装置。设计了不锈钢介质槽及安装机构;利用现有铁路罐车容积量传系统,采用光栅尺位移传感器作为标准器,水为测量介质,计算机控制步进电机驱动位移传感器和摄像头在导轨上移动,通过软件获得标准器和被检液位计液位数据;设计了大量程磁致伸缩液位计的测量结构和测量方法;分析计算了介质密度对测量结果的影响及修正;评估了测量不确定度,满足磁致伸缩液位计或其他浮子式液位计量值溯源的需要。     

脉宽调制(PWM)实现步进电机的细分驱动技术

步进电机作为一种控制电机,其控制精度(分辨率)取决于步距角的大小,单纯地靠机械手段降低其步距角是有限的。常采用细分驱动技术。着重介绍脉宽调制(PWM)实现的步进电机细分驱动技术,该技术不仅可以提高步进电机的分辨率,还可以克服步进电机在低速时易出现的低频振动现象。     

游标卡尺示值检定装置设计

游标卡尺示值一直采用人工目视检定方法,效率低下.设计了一种游标卡尺示值检定装置,其中精密基座系统设计采用弹性力学理论,建立动态力学特性模型.基于模型分析计算刚度等参数,确定精密基座系统的设计结构.为了有效减少系统阿贝误差,检定装置系统控制其允许出现的最大倾斜角.根据步进电机速度曲线原理,设计电机驱动器有效的细分数.在符合JJG30-2012《通用卡尺检定规程》要求下,采用高精密度光栅尺替代标准量块,步进电机代替人工操作,图像识别技术代替人眼,提高了游标卡尺的检定效率,实现了计管控一体.     

Magnetic Properties of Diluted Magnetic Nanowire

A magnetic diluted nanowire with cylindrical structure described by the Ising model is investigated. Using the effective field theory with a probability distribution technique, the influence of the dilution on the phase diagrams, susceptibility and the hysteresis loops are discussed in detail. Novel features are obtained for the thermal variations of longitudinal susceptibility and longitudinal magnetization. We have investigated the magnetic reversal of the system and have found the existence of triple hysteresis loops patterns, affected by the concentration of magnetic atoms, the temperature, and the exchange interaction between the core and the surface shell.     

Tweezing of Magnetic and Non‐Magnetic Objects with Magnetic Fields

Although strong magnetic fields cannot be conveniently “focused” like light, modern microfabrication techniques enable preparation of microstructures with which the field gradients – and resulting magnetic forces – can be localized to very small dimensions. This ability provides the foundation for magnetic tweezers which in their classical variant can address magnetic targets. More recently, the so‐called negative magnetophoretic tweezers have also been developed which enable trapping and manipulations of completely nonmagnetic particles provided that they are suspended in a high‐magnetic‐susceptibility liquid. These two modes of magnetic tweezing are complimentary techniques tailorable for different types of applications. This Progress Report provides the theoretical basis for both modalities and illustrates their specific uses ranging from the manipulation of colloids in 2D and 3D, to trapping of living cells, control of cell function, experiments with single molecules, and more.     

Magnetic Properties of Chalcopyrite-Based Diluted Magnetic Semiconductors

We calculated the chemical trends of transition metal-doped chalcopyrite DMS (diluted magnetic semiconductors) by the use of KKR–CPA–LDA method. The ferromagnetism was stable in V- and Cr-doped chalcopyrite DMS. In the case of Fe and Co doping, however, the spinglass-like state was realized. On the other hand, in the cases of Mn doped I-III-VI₂ and II-IV-V₂ type DMS, the ground state was ferromagnetic and spinglass-like, respectively.     

铁硅铝磁粉芯的磁特性研究

采用球磨制粉和模压成型方法制备了铁硅铝磁粉芯,并研究了其频率特性和直流叠加特性。结果表明,在测量的频率范围内（1～500kHz）,铁硅铝磁粉芯有效磁导率基本保持不变,而品质因数随频率的增加而增大,达到峰值后缓慢下降。在相同频率下,随着粉料粒度的减小,磁粉芯的有效磁导率降低,品质因数增加。铁硅铝磁粉芯具有良好的直流叠加特性,当直流偏磁场强度为1000e时,其有效磁导率变化率小于50％,且减小磁粉粒度可改善磁粉芯的直流叠加特性。     

磁编码器多极磁鼓材料的研究

通过分析磁编码器磁鼓的结构和制作工艺，研究采用粘结磁性材料做磁编码器用磁鼓材料。粘结磁体采用硅烷为偶联剂，环氧树脂为粘合剂。研究了不同组份的配方对磁鼓材料的影响。制备出了Ｂｒ＝１２７７Ｇｓ，Ｈｃ＝１０７９Ｏｅ，（ＢＨ）ｍａｘ＝０．５３ＭＧＯｅ的磁鼓材料。     

Tailoring of Magnetic Properties of Magnetostatically-Coupled Glass-Covered Magnetic Microwires

We report on tailoring of magnetic properties of Fe- and Co-rich microwires through magnetostatic coupling among them. We studied hysteresis loops of the arrays containing different number of the Co₆₇Fe_3.9Ni_1.5B_11.5Si_14.5M_0.6 and Fe₇₄B₁₃Si₁₁C₂ amorphous microwires. Fe₇₄B₁₃Si₁₁C₂ microwires have rectangular hysteresis loop, while Co₆₇Fe_3.9Ni_1.5B1_1.5Si_14.5M_0.6 with vanishing magnetostriction constant posses inclined hysteresis loop with low coercivity. The presence of neighboring microwire (Fe either Co-based) significantly modifies hysteresis loop of whole microwire array. In a microwire array containing Fe-based microwires, we observed splitting of the initially rectangular hysteresis loop with a number of Barkhausen jumps correlated with number of Fe-rich microwires. In Co?CCo arrays, we observed a change of inclination of overall hysteresis loop, and consequently magnetic anisotropy field under influence of the additional of Co-based microwire. In the case of mixed arrays containing Fe and Co-rich microwires, we were able to obtain irregular hysteresis loops with unusual shape. In this case, considerable increase of harmonics has been observed. Magnetic field amplitude and frequency affect the behavior of all studied arrays. Increasing the amplitude the shape of hysteresis loop of microwire array containing Fe-based microwires transforms from multi-step to single above certain magnetic field amplitude. In the array with Co-based microwires, we observe a change of coercivity. Observed dependences have been attributed by us to the magnetostatic interaction between the microwires with different magnetic domain structure. Together with the conventional method, such as thermal treatment, designing of arrays containing different types of microwires can serve for tailoring of their magnetic properties.     

Comparison of Magnetic Field Analysis Methods Considering Magnetic Anisotropy

The magnetic field analysis results on grain-oriented silicon steel sheet and nongrain-oriented silicon steel sheet by the isotropic method, the two-axis isotropic method, the two-axis anisotropic method, the $varphi$ anisotropic method, and the $theta_{rm HB}$ anisotropic method, which are 2-D magnetic analysis methods, are compared. In analyzing the magnetic field in the isotropic material, the isotropic method is more appropriate than the two-axis isotropic method. For the anisotropic material in which the magnetic flux density is much less than saturation magnetic flux density, the two-axis anisotropic method is more preferable than the $varphi$ anisotropic method, because the result of the two-axis anisotropic method is similar to that of the $theta_{rm HB}$ anisotropic method. However, for the analysis in high magnetic flux density near the saturation magnetic flux density, the $varphi$ anisotropic method is more suitable than the two-axis anisotropic method.      

磁旋转编码器多极磁鼓的研制

在分析磁骗码器的原理和结构的基础上，采用粘结磁体作磁编码器多极磁鼓记录介质材料，运用体成型工艺，研制出了多种型号的磁鼓。同时对磁鼓进行了充磁和气隙磁性能分析。     

磁性Fe3O4纳米颗粒的制备和磁性研究

讨论了一种制备磁性Fe3O4纳米颗粒的新方法，利用自行设计的反应容器，引入磁场和电场的相互作用，制得颗粒大小比较均一、分散性较好的Fe3O4纳米颗粒。通过改变反应时间、磁铁高度，得到了平均粒径为5～10nm的Fe3O4纳米颗粒，并对其进行磁特性测量。     

磁悬浮运动平台的磁场分析及优化设计

研制了一种新型磁悬浮平台,该平台定子采用无铁心式的克莱姆绕组,消除了固有齿槽效应,动子采用Halbach 磁阵列结构方式,由于平台输出推力与悬浮的稳定性主要与其气隙磁场的分布情况有直接关系,因此提高气隙磁场的正弦分布是改善其工作特性的难点和重点. 为了改善气隙磁场的分布问题,提出了一个优化磁场分布的目标函数,并采用步长加速法对平台磁场进行了优化设计,大大降低了磁场谐波分量,改善了气隙磁场分布状态. 将优化结果运用到实际的平台中,对该运动平台进行了阶跃响应实验,实验结果表明满足平台需要达到纳米级精度的要求.