The core of the motor domain determines the direction of myosin movement

Myosins constitute a superfamily of at least 18 known classes of molecular motors that move along actin filaments. Myosins move towards the plus end of F-actin filaments; however, it was shown recently that a certain class of myosin, class VI myosin, moves towards the opposite end of F-actin, that is, in the minus direction. As there is a large, unique insertion in the myosin VI head domain between the motor domain and the light-chain-binding domain (the lever arm), it was thought that this insertion alters the angle of the lever-arm switch movement, thereby changing the direction of motility. Here we determine the direction of motility of chimaeric myosins that comprise the motor domain and the lever-arm domain (containing an insert) from myosins that have movement in the opposite direction. The results show that the motor core domain, but neither the large insert nor the converter domain, determines the direction of myosin motility.     

运用转矩星形图分析直线步进电动机的步进运动

在旋转步进电动机的步进运动分析中,转矩星形图是一种比较有效的工具.直线步进电动机可以看成是由旋转步进电动机演变而成的,因此借鉴旋转步进电动机的分析方法,引入转矩星形图,简明直观地分析计算了各种供电方式下,直线步进电动机步进运动时的动子齿运动和电磁力变化情况以及静态定位误差.     

Development of an underactuated prosthetic hand with the step motor

0IntroductionThe design condition of electromyography(EMG)prosthetic handis different fromthe industrial robot handmainlyinits decorative nature,weightlimit andfunction.Generally commercial prosthetic hands are basically sim-ple grippers having one or two DOF(degree of freedom),which cannot meet the needs of the users[1].In thisstudy,we developed a multi-fingered anthropomorphicrobot handfor the EMGprosthetic handto realize activityof dailyliving[2].Based on underactuated mechanism[3],andt…     

步进电机细分驱动技术综述

阐述了步进电机的细分驱动原理。介绍了单片机控制的放大型、斩波式、脉宽调制式等步进电机细分驱动电路的结构和控制原理,指出了各种驱动电路的应用场合和对小进电机细分驱动的相电流控制策略。     

步进电机在柴油机VGT控制中的应用

采用可变几何涡轮增压器(VGT)是改善增压柴油机低工况的有效方法.在此,介绍了一种以STC89C52单片机为核心,输入采用光电隔离,输出采用集成驱动芯片,对步进电机进行控制的方法,实现对VGT的控制.试验表明,设计方案是可行的,具有一定的实用价值.     

基于STM32的步进电机转速控制实验设计

STM32包含Cortex-M3内核,具有低功耗,丰富片内外设,处理速度快等特点,典型应用于数据采集处理系统。文章介绍了一种基于STM32的步进电机转速控制实验设计。与传统的单片机电机控制相比,它具有处理速度快,功能完善等优点。STM32根据送入的传感器信号操控电机运转,并显示电机工作状态。文章给出了具体的实验电路的硬件设计及软件设计流程,并给出部分实验说明。经实践证明该实验系统稳定可靠,具有较好的实验教学效果。     

大力矩行波超声电机的性能

研制了一种新结构、大力矩行波型的超声电机。该超声电机中,压电片被粘接到金属体上构成振动体,作为转子,并与外壳接触。电机的外壳兼作定子。通过转子、定子之间的摩擦力驱动转子转动。这种电机结构除减少了单独的转子部件外,还提高了超声电机的力矩输出性能。利用有限元方法对电机的转子进行优化设计,计算了直径100mm的行波超声电机的转子的模态。根据设计制作出样机。并对样机性能进行了测试,堵转力矩超过了4N.m。该电机具有重要的应用前景。     

基于FPGA的步进电动机平滑运行设计

用现场可编程门阵列（FPGA）实现步进电机平滑运行．设计了基于FPGA的步进电机平滑运行系统框图和具体电路．仿真及实际运行效果表明，系统具有较好的性能和一定的实用价值．     

基于FPGA的混合式步进电动机微步驱动研究

针对混合式步进电动机开环运行时的振荡和失步问题,介绍一种以A ltera公司的可编程逻辑器件EP1C6Q240C8为核心实现的两相混合式步进电动机系统.实验结果表明：采用该控制方式实现的两相混合式步进电动机系统具有无低频振荡、分辨率高和运行平稳的特点.     

基于单片机的步进电机控制系统的研制

以AT89S51单片机为核心构成步进电机的控制系统。设计了步进电机驱动电路、键盘设定与显示电路,并进行了系统软件设计。重点阐述了脉冲产生电路以及对速度的控制。该系统成本低、控制方便、控制精度高。     

Structure of the C-terminal domain of FliG, a component of the rotor in the bacterial flagellar motor.

Many motile species of bacteria are propelled by flagella, which are rigid helical filaments turned by rotary motors in the cell membrane. The motors are powered by the transmembrane gradient of protons or sodium ions. Although bacterial flagella contain many proteins, only three-MotA, MotB and FliG-participate closely in torque generation. MotA and MotB are ion-conducting membrane proteins that form the stator of the motor. FliG is a component of the rotor, present in about 25 copies per flagellum. It is composed of an amino-terminal domain that functions in flagellar assembly and a carboxy-terminal domain (FliG-C) that functions specifically in motor rotation. Here we report the crystal structure of FliG-C from the hyperthermophilic eubacterium Thermotoga maritima. Charged residues that are important for function, and which interact with the stator protein MotA, cluster along a prominent ridge on FliG-C. On the basis of the disposition of these residues, we present a hypothesis for the orientation of FliG-C domains in the flagellar motor, and propose a structural model for the part of the rotor that interacts with the stator.     

A single amino acid in the glycosyl phosphatidylinositol attachment domain determines the membrane topology of Fc gamma RIII

Cell-surface proteins are associated with the lipid bilayer either as membrane-spanning molecules or as glycosyl phosphatidylinositol (GPtdIns)-linked proteins. Proteins destined for GPtdIns anchoring are synthesized as precursors with a hydrophobic C-terminal transmembrane domain, which is removed during the processing of these proteins in the endoplasmic reticulum (ref. 1). We have investigated the structural requirements for GPtdIns anchoring through the study of two closely related proteins which exhibit alternative membrane attachment. The IgG Fc receptor, Fc gamma RIII, is GPtdIns-linked on neurophils (III-1) whereas on natural killer (NK) cells and macrophages it is found as a transmembrane-anchored molecule (III-2), able to mediate antibody-dependent cellular cytotoxicity and phagocytosis. At the primary structural level, the III-1 gene differs from that encoding III-2 by only nine nucleotide substitutions, which result in six amino-acid differences, and the absence of 21 amino acids at the C terminus. We have analysed a series of III-1 and III-2 mutants in transient expression assays, and show that Ser 203 in the GPtdIns attachment domain is the dominant residue in determining whether the molecule can be GPtdIns-anchored. As in the case of its murine homologue, Fc gamma RII alpha, surface expression of the III-2 molecule is dependent on co-expression of a second subunit, the gamma chain of F epsilon RI. Our data also suggest that gamma chain can associate with the III-1 precursor, preventing GPtdIns attachment, favouring instead a transmembrane form.     

基于PCI-1750数据采集卡的步进电机控制系统设计

为了方便可靠地控制步进电机,设计了基于"PC+数据采集控制卡"的系统控制方案.通过VC++6.0调用数据采集控制卡中的运动函数库,动态改变脉冲频率,控制电动机的转向和转速,实现步进电机的多轴运动控制.实验表明该控制系统能够很好地满足控制要求.     

Research on the variable speed system of large power alternating current motor

The development status of the variable speed system of large power AC(alternating current)motor drive in China is introduced.The large power AC drive fed by AC-AC converters(cycloconverters)has developed greatly,and some innovations on the theory and engineering technique have been realized.They have been applied to rolling mills,mine hoists,and so on,and remarkable economic and social benefit has been achieved.The development of AC drive fed by large power IGCT(integrated gate commutated thyristors)AC-DC-AC converter is also introduced.It has excellent performance and reliable operation,and has been used in traction.     

大功率交流电机变频调速技术的研究

论述了我国大功率交交（AC-AC）变频调速技术的研究和国产化装备的研制工程,丰富并完善了大功率交流调速理论,形成了自主创新的核心技术,解决了大功率交流调速装备的多项关键技术,推动国产交流调速装备步入国际先进行列,立足工程,取得显著的经济效益和社会效益;并介绍了我国第一套7.5 MVA三电平IGCT交直交（AC-DC-AC）变频调速系统的研制,该变频器结构紧凑、性能良好、运行可靠,达到国际先进水平。     

PLC控制的步进电机频率曲线优化技术研究

PLC(Programmable Logic Controller)控制步进电机在许多工业控制中应用广泛,本文介绍了PLC通过发送脉冲和方向信号给步进电机的驱动器,由驱动器来控制步进电机工作的原理.并研究了步进电机的频率曲线,分析总结出用PLC控制步进电机使运动小车的运行速度最优化,并在中药自动配药系统中以实验数据证明了步进电机在PLC控制下的频率曲线优化的可行性.     

大型电机远程实时监测系统的设计

针对工业现场大型电机运行状态的实时监测,设计出了一种以AVR单片机为控制核心的监测系统。系统主要分为监测模块部分和上位机监测部分。监测模块部分以微处理器为核心,对大型电机运行状态的电量参数以及温度进行采集,并将信息上传给上位机。上位机可对现场监测节点进行数据显示。介绍了各主要部分电路以及系统软件。系统结构设计简单,可靠性强,具有良好的工业应用价值。