浅谈步进电机的基本原理

步进电机作为执行元件,是机电一体化的关键产品之一,广泛应用在各种自动化控制系统中。随着微电子和计算机技术的发展,步进电机的需求量与日俱增,在各个国民经济领域都有应用。步进电机是一种将电脉冲转化为角位移的执行机构。当步进驱动器接收到一个脉冲信号,它就驱动步进电机     

斩波恒流细分驱动

步进电机作为机电一体化的重要产品之一,广泛的应用在各种自动控制系统中,用来实现对生产过程中有关设备的控制与调节,随着生产中对控制系统的速度及精度要求的越来越高,对步进电机的要求也越来越高。,本设计中斩波恒流细分驱动方案,以充分发挥微步进驱动方式的优越性,同时选择了一条比较理想的升降速曲线,以解决步进电机高速启停过程中的失步和过冲问题,从而进一步提高步进电机的工作性能,使其更加快速稳定的运行,以达到优化控制的目的。     

基于FPGA的高精度自动调速步进电机控制器

针对现有步进电机控制器的不足,提出了一种基于FPGA的高精度步进电机控制器方案,实现了速度的自动调节和规划功能.其主控制器MCU设定运行距离、速度、启动速度以及减速距离等变量,该控制器将自动实现步进电机的速度控制和位置控制.     

全电动注塑机差动式合模机构的设计与分析

对全电动注塑机差动式合模机构进行结构设计,并对差动式齿轮机构的功率流向进行分析.差动式合模机构将异步电动机和步进电机生成的输入运动通过两个自由度的ZUWGW型2K-H差动轮系合成后,产生可编程的输出运动.同时异步电动机和步进电机混合驱动,其中异步电动机提供较大的功率,步进电机起调节的作用,二者的组合有效地代替了大功率步进电机,从而能实现高锁模力、高效率、运行速度快、低能耗、低成本.     

用Z—80单板机控制步进电机

步进电机在数字控制系统中作为数/模转换器应用甚广。本文将以三相步进电机为例,介绍用Z—80单板机对步进电机进行速度和位置控制的接口电路及其编程方法。利用Z—80单板机的并行输入/输出接口PIO和少量外围电路,即可实现对步进电机的控制。控制装置的电原理图如图1所示。     

基于彩色光/频转换器的新型旋光仪设计

采用业界首款数字彩色光/频转换器芯片TCS230设计一款新型旋光仪。运用软件算法判断旋光方向,并应用LED光源、红外测温、半导体制冷、步进电机细分驱动等相关技术,实现数字化、低功耗、低成本、高性能设计。     

可自启动多模式三相环形脉冲分配器的设计

提出了一种可自启动的多模式三相步进电机环形脉冲分配器的设计方法。首先,通过分析各模式的状态转换关系分别获得各模式下的触发器驱动方程,进而产生模式可选的触发器驱动方程。其次,由驱动方程设计出简化的硬件电路。最后,对自启动进行了讨论,给出了自启动电路设计。实际电路可通过模式设置获得三相单三拍、三相双三拍和三相六拍等三种环形脉冲分配器。     

基于单片机的步进电机控制系统设计

采用单片机AT89C51对步进电机进行控制,通过I/O口输出的具有时序的方波作为步进电机的控制信号,用5个按钮来对电机的状态进行控制,利用MAX232接入计算机串行通信接口芯片将软件设计程序输入到单片机里,单片机根据电机的状态信号将写入的程序通过CPU进行处理,发出脉冲控制信号,脉冲控制信号经过芯片ULN2003A驱动步进电机,步进电机将脉冲控制信号转换为电机的角位移,使电机的转子根据脉冲数来实现电机准确的转速控制。采用74LS164作为6位单个数码管的显示驱动,CPU根据发送过来的指令进行相应的动作,从而使数码管能够显示出相应的转速,同时步进电机也根据脉冲信号的频率和脉冲数开始旋转。通过实际调试,步进电机能够实现正转、反转、加速、减速等功能。     

工程机械轮胎胎面仿型缠绕成型机设计

介绍工程机械轮胎胎面仿型缠绕成型机的主要结构和仿型过程。该机选用普通电机配合变频调速器 ,采用一级同步带减速和滚珠丝杠驱动成型头在平面导轨上移动 ,减小了电机体积和驱动器惯性 ,保证了运行的平稳性和正反转的灵敏度 ,并节省了维护时间 ,提高了生产效率     

高精度微量恒流泵控制器

高精度微量恒流泵控制器主要用来控制HW型微量恒流泵,也适用于以步进电机为动力的各种装置。HW型微量恒流泵适用于化学反应动力学、液相色谱技术以及其他多种研究工作。它的特点是排液流量十分微小(2微升/分),最小可调节流量值亦十分微小(±1微升/分)。控制器的任务是根据所要求(设定)的排液流量,发生相应频率的脉冲,控制步进电机的转速,使泵按照设定流量值恒定地排液。因此,控制器发生的脉冲应满足:(1)频率极其稳定;(2)脉冲宽度和间隔均匀;(3)频率应能作精细的调整,以适合最小可调节流量(相应的频率变化量为±0.71赫兹)的需要。能否达到这些基本要求是控制的关键。步进电机控制电路的种类很多,如驰张振荡器、压控振荡器、各种稳态电路、波形发生电路、晶体振荡分频电路。这些电路都属于开环     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.