外部干扰的抑制(四)

6．2．6抑制滑环现在市场上很容易买到在几吉赫兹频率上具有优异性能的滑环,但使用滑环进行供电时,很容易引起电火花,从而产生电磁干扰,腐蚀滑环的接触区域,降低滑环的寿命。     

中频滑环的设计

本文借助微波理论,用信号流程图的方法来求解中频滑环传输特性的数学表达式,并用作设计依据。通过对滑环特殊部位的分析,可以得出整个滑环特性形象的概念,明确改善滑环性能的途径。     

用准分子激光器制造碳化硅滑环微型结构

用准分子激光器制造碳化硅滑环微型结构１．引言滑环密封用于高压下旋转轴穿透位置上液体密封技术的所有领域，通常采用烧结陶瓷碳化硅（ＳｉＣ）作密封环材料。它具有耐化学性好、热传导性好等特性．是利于摩擦的滑动面精细结构（表１）。同石墨对接面结合，具有高磨损强...     

滑环副的研制概况

结合工作实际，介绍近几年来滑环摩擦副的研制概况。以等效试验、摩擦副的选配和接触电阻的测量为主要内容，举出部分试验数据。     

基于光纤滑环的旋转部件温度测量

提出由两个准直镜构成用于实现离轴旋转连接的光纤滑环,利用其与光纤布喇格光栅传感器结合,获得轴心被占用或为空心轴时旋转部件上温度测量的新方法。分析了影响光纤滑环插入损耗的主要因素,指出插入损耗对两准直镜间的横向错位和轴向夹角的变化很敏感,而对轴向间距的变化略显迟钝。旋转部件匀速转动过程中,光纤滑环的耦合信号为周期脉冲信号,测得信号的占空比为0.5%,与理论值基本相符。并利用光纤滑环对光纤布拉格光栅传感光路的耦合,实现旋转部件上待测温度场升温过程的实时观测,从而验证了此测量方法的可行性。     

无线电的传输

在对大直径超长钢管、钢棒的无损检测中,用多通道旋转探头来采集信号,用滑环来传送信号,由于滑环同时又要传送磁化电流,这就给传送的可靠性带来了问题。在分析了基于滑环传送方式中所存在问题的基础上,提出了基于软件无线电的缺陷信号传输方式,将磁化电流和缺陷信号分开传送,经实践验证该方法能有效解决原系统中存在的缺陷,并且传送信号的准确度有了很大的提高。     

无线通讯系统在连续式卸船机的运用

原卸煤机与控制室之间的通讯采用滑环及电缆卷盘方式连接。随着使用时间的推移，故障较多。本文介绍通过无线方式连接卸船机及控制室的PLC系统，具有更高的安全等级、更高的可靠性。     

众望达推出高性能光纤滑环

一直致力于为客户提供圆满技术解决方案的众望达技术，为解决高端用户对高速旋转连接的系统部件之间的高带宽、高速率的数据传输问题．特推出一系列高效光纤滑环（光纤旋转连接头）。     

滚仰式光学滑环的测角分析

滚仰式光学滑环被广泛应用在小型化位标器中。由于引入了折转光路,其对目标的空间角位置测量比传统的跟踪成像系统更复杂。基于光线反射定律和等距变换理论研究滚仰式光学滑环对目标的空间角位置测量,得到理论计算公式和近似计算公式,最后通过数值仿真验证了分析结果的正确性。     

大电流旋转电滑环的研制

利用旋转电滑环可以实现在转动状态下传输信号和电源动力,并使传输信号和电源动力的电缆不会发生扭绞性损坏,既保证了电缆的收放,又保证了系统的电气连接.介绍了这种新型旋转电滑环的结构、技术指标,重点对产品的设计方案、材料选择、电气参数等进行了分析.     

Electronic control of alternator excitation by gyrators and nonreciprocal networks

A method is described for exciting an alternator from currents in the stator. The rotor is thereby greatly simplified. No slip rings, no rotating rectifiers and no elaborate flux paths are required. The method has been verified experimentally in a version with two amplifiers of unit gain in place of a gyrator. Other proposals are described and involve only passive elements external to the alternator.     

Design of a pin-on-disc-type CNC tribometer including an automotive dry clutch application

The paper presents the design of a pin-on-disc type tribometer intended for experimental characterization of static and dynamic friction behaviors for various sliding sample pairs. The normal force, slip speed, and temperature, as the main influencing parameters, are precisely controlled during experiments, by applying vertical and rotational servo-axes and an electric heater built in the rotating disc. A compact three-axial piezoelectric force sensor, placed between the vertical-axis screw drive and the friction sample, provides direct measurement of normal and tangential forces used to calculate the sample coefficient of friction. The slip speed is measured directly using an incremental encoder mounted at the rotational table. The disc temperature is measured by a built-in Pt probe, whose wires, together with the heater wires, are connected to the temperature control unit by means of slip rings. The tribometer performances are demonstrated through a study of coefficient of friction, shudder sensitivity, and wear rate characterization for a dry clutch friction material.     

Directed Self‐Assembly of Gradient Concentric Carbon Nanotube Rings

Hundreds of gradient concentric rings of linear conjugated polymer, (poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐ phenylenevinylene], i.e., MEH‐PPV) with remarkable regularity over large areas were produced by controlled “stick‐slip” motions of the contact line in a confined geometry consisting of a sphere on a flat substrate (i.e., sphere‐on‐flat geometry). Subsequently, MEH‐PPV rings were exploited as a template to direct the formation of gradient concentric rings of multiwalled carbon nanotubes (MWNTs) with controlled density. This method is simple, cost effective, and robust, combining two consecutive self‐assembly processes, namely, evaporation‐induced self‐assembly of polymers in a sphere‐on‐flat geometry, followed by subsequent directed self‐assembly of MWNTs on the polymer‐templated surfaces.     

A novel Variable-Reluctance Resolver proposal and its performance analysis under healthy and eccentric cases

A Variable-Reluctance resolver (VR-Resolver) with a novel structure is proposed in this paper as an absolute position sensor, where two possible structures are analyzed. The signals and excitation windings are located on the stator. Hence the slip rings are eliminated in the rotor. The rotor is considered by slot/teeth configuration so the rotor is shaped in a simple variable reluctance structure with a low sensitivity to the manufacturing tolerance. The excitation winding is wound in toroidal configuration that leads to having a smaller fill factor as well as turns can be considered for the windings. Maximum position error (MPE) is evaluated for the proposed resolvers in both healthy and eccentric cases. Therefore, the resolvers performance and their sensitivity to the eccentricity fault are evaluated. A flexible Magnetic Equivalent Circuit (MEC) with adjustable accuracy is used for modeling thanks to its capability and shorter processing time compared to the Finite-Element Method (FEM), where different cases are analyzed by a unique MEC model. Finally, comparison between the MEC and FEM-based results as well as experimental tests are presented to show effeteness of the proposed resolver as an accurate absolute position sensor for industries applications.     

纵向打滑状态下的轮式移动机器人编队控制

针对轮式移动机器人车轮纵向打滑时的编队控制问题,提出一种基于滑移率补偿和模糊逻辑的多机器人编队控制器设计方法.首先,利用速度传感器获取机器人的实际速度信息,并进行滤波减少传感器噪声.结合速度输入指令信号得到滑移率估计值,用以描述机器人纵向打滑的程度.然后根据领航跟随法,设计补偿纵向打滑的编队控制策略,并采用模糊逻辑设计控制器参数.最后在Microsoft Robotics Developer Studio 4（MRDS4）中搭建3D物理仿真平台,进行编队控制仿真,验证了领航、跟随机器人发生打滑的情况下所提方法的有效性.     

汇流环技术的研究与发展

论述汇流环技术的研究进展。分析了汇流环的主要电性能指标,其中包括接触电阻、绝缘电阻、电介质强度、串扰、电噪声及驻波比等;针对汇流环电接触件结构、电接触材料及零部件制造工艺等方面的研究发展现状分别进行阐述;探讨了汇流环未来的发展方向:小型化、集成化以及向民用领域拓展。     

光纤旋转连接器在雷达系统中的应用

随着雷达技术的不断发展,光电组合式汇流环将逐步代替传统电汇流环。由于光电组合汇流环在性能上和结构上结合了电汇流环和光纤旋转连接器的优点,如结构坚固、可靠性高、耐恶劣环境、抗电磁辐射、数据传输量大、传输速度快、信号损耗小等,同时减少了系统互连用的电缆数量,所以是雷达信号传输的一个新的发展方向。本文对光纤旋转连接器做了介绍,并和电汇流环进行了对比分析,接着对光纤旋转连接器的安装、光纤旋转连接器雷达信号的传输方案进行了介绍。     

光纤通信技术在光电经纬仪中的应用

光电经纬仪等光电跟踪测量仪器在数据传输过程中，方位轴上的导电环存在传输速率低、带宽窄、抗电磁干扰能力差的问题，当数据量较大时，导电环无法实现实时传输，针对这些问题，提出了用光纤取代导电环的方法。在原导电环位置安装一对光准直器，利用光能够在空气中传播的特点，实现光信号在两段光纤之间的耦合。从而将电信号的接触式传播变为光信号的非接触式传播。光纤传输的优点使设备的整体性能得到提高。     

Property Analysis of the Rough Slider Bearings in Micromotors for MEMS Applications

Based on the kinetic theory of gases, a new slip model is applied for the gas-lubricated Rayleigh slider bearings beneath three bushings of a micromotor in microelectromechanical systems (MEMS). A modified Reynolds equation is established by taking into account of the coupling effects of gas rarefaction and roughness and then analytical solutions for pressure distribution, load-carrying capacity and its streamwise location, and velocity profile are obtained for various slider-bearing configurations. The new slip model is validated by comparisons with the results presented in other researchers’ works. It is indicated that the present new slip model is of better accuracy in predicting the bearing properties than the first-order, second-order slip models, and modified molecular gas lubrication model and is a good approximation to variable hard sphere and variable soft sphere models. The solutions provided by the present new slip model match the solution obtained using the linearized Boltzmann equation very well. The results also show that the coupled effects of gas rarefaction and roughness are of great significance in the design of the bushings for slider bearings in micromotors.      

迭代学习控制在飞机全电刹车系统中的应用

飞机全电刹车系统具有传统的液压刹车系统不可比拟的优势,是未来飞机刹车系统的发展方向。针对现有液压刹车系统控制律的不足和全电刹车系统的特点,建立了以飞机纵向速度、滑移率为状态变量,滑移率为输出变量的刹车系统非线性状态方程。根据滑移率与结合系数的关系,在线辨识不同路面条件下的最大结合系数和最佳滑移率,提出了在常规PI控制器的基础上,施加一D型迭代学习前馈控制器的控制策略,以提高系统的快速跟随性,并将最佳滑移率作为迭代学习控制的期望输出。经过对干跑道状态下的仿真验证,表明加入迭代学习控制律后,可以满足飞机全电刹车系统的技术性能,在刹停时间、刹停距离及刹车效率等方面得到了改善,具有良好的收敛速度、稳定性和跟踪性。