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1A:1:Afeedbacksystemisoftenbetterabletocopewithunexpecteddisturbancesanduncertaintiesaboutthesystem’sdynamicbehavior.一个反馈系统经常能更好的应付不期望的扰动作用以及系统动态性能的不确定性,//However,itneednotbetruethatclosed-loopcontrolisalwayssuperiortoopen-loopcontrol.然而,闭环控制并不一定总是优于开环控制,//Whenthemeasuredoutputhaserrorswhicharesufficientlylarge,andwhenunexpecteddisturbancesarerelativelyunimportant,closed-loopcontrolcanhaveaperformancewhichisinferiortoopen-loopcontrol.当输出的测量误差足够大或不期望的扰动无关紧要时,闭环控制的性能就会比开环控制的差2:Ananalog--to--digitalconverter(ADC)isusedtoconvertacontinuouslyvariablesignaltoacorrespondingdigitalformwhichcantakeanyoneofafixednumberofpossiblebinaryvalues.一模拟--数字转换器(ADC)用来将连续变换信号编程相应的数字量,这数字量可是可能的二进制数值中的一固定值。3:Anewphaseinrobotapplicationshasbeenopenedwiththedevelopmentof“intelligentrobot”.一个机器人应用的新局面随着“智能机器人”的发展而已近打开。24:Anexampleisthespeedcontrolsystemofaturbine-generatorsetinapowerstation,whosemainpurposeistomaintainthegeneratorspeedasnearlyconstantaspossible。电厂涡轮发电机组就是一个例子,它的主要目的是维持发电机的转速尽可能的接近于恒值。5:Anexampleofthistypeofsensorswouldbeavisionsensorusestolocateandidentifyobjectsandpositionoftherobotitself,combinedwithatactilesensorusedtodetectthedistributionofforceandpressure,anddeterminetorque,weight,centerofmassandcomplianceofthematerialithandles.这类传感器的一例是视觉传感器,用于对物体和机器人本身的定位和辨别;并结合触觉传感器用于探测力和压力的分布和确定力矩,质量,重心,按所抓取的材料决定握持力。//Thehand-eyecoordinationforgeneral-purposemanipulationwillbeextremelypowerfulintheindustrialworld.这种用于通用的手眼配合操作在工业界将会变得极为有效力。6:Arobot,onceproperlyprogrammed,willnotputachipinthewrongplace.一旦适当地编程,机器人就不会将芯片发错地方。C:1:Caremustbetakenwhenconnectinglogiccircuitstoensurethattheirlogiclevelsandcurrentratingsarecompatible3连接逻辑电路时,必须小心翼翼,以保证它们的逻辑电平和电流额定值是兼容的。//Theoutputvoltagesproducedbyalogiccircuitarenormallyspecifiedintermsoftheworstcasevalueswhensourcingorsinkingthemaximumratedcurrents.由逻辑电路产生的输出电压通以拉出或灌入最大额定电流时,按最弱情况下数值说定义。2:Considerthearmature-controlledD.C.motorshownschematicallyinFig.25.1.图25.1是电枢控制的直流电机。//Suchmotorsarefairlycommoncomponentsinsystemsofinteresttocontrolengineers.这种电机是控制工程师在系统中应用的比较普遍的元件。//Thetorquem(t)developedbythemotorandhenceitsangularvelocityw(t)(orinsomeapplications,itsangularposition)arecontrolledbyvaryingthevoltagev(t)appliedtothearmaturewinding.可以靠改变电枢绕组上的电压v(t)去控制电机的转矩m(t),从而控制角速度w(t)(在某些应用中为角位移)。//Thestator(field)windingisconnectedtoaconstantvoltagesource,sothatthecurrentandhencethemagneticfluxφfinthefieldwindingareapproximatelyconstant.定子(磁场)绕组接到恒压电源上,因此其电流所产生的磁场中的磁通φf是接近于常数的。D:1:DenotingthemassmomentofinertiaofthearmatureasJ,andassumingthatthereisanexternallyappliedloadtorque4mL(t)andaviscousfrictiontorqueCw(t)opposingthemotion,wemaywrite设电枢的转动惯量为J,外加负载转矩为mL(t),摩擦转矩为Cw(t),两者都是阻碍运动的,于是得E:1:Everytimetheinterfaceisusedtoreadatransducer,thesameoperationsmustbecarriedouttoconverttheinputnumberintoamoreconvenientform.接口总是用于读取传感器的值,同时还要将输入数值转换成更容易的形式。F:1:Fig1.4showsvolt-amperecurvesforametalfilamentlamp,V1(Ⅰ),andforacarbonfilamentlampV2(Ⅰ),图1.4中的曲线V1(Ⅰ)和V2(Ⅰ)分别表示-金属丝灯泡和碳丝灯泡的伏-安特性曲线,//Asisseen,therelationbetweenthevoltageandthecurrentineachlampisotherthanlinear.如图所示每个灯泡的电流和电压之间的关系并不是线性的,//Theresistanceofthemetal-filamentlampincreases,andthatofthecarbon-filamentlampdecreaseswithincreaseofcurrent.随着电流的增加,金属丝灯泡的电阻是增加的,而碳丝灯泡的电阻是减少的。2:Figure21.1showsacommonapplicationofautomaticcontrolfoundinmanyindustrialplants.图21.1显示出了在许多工业工厂所见到的常用的自动控制应用。3:Fig.37.1isageneralrepresentationofanopen-loopcontrolsystem.图37.1是对开环控制系统的一般性表示。//Theinputorcontrolu(t)is5selectedbasedonthegoalsforthesystemandallavailableaprioriknowledgeaboutthesystem.输入变量或控制作用u(t)是根据本系统的目标以及所有可获取的先验知识而选定的。//Theinputisinnowayinfluencedbytheoutputofthesystem,representedbyy(t).输入变量绝不会受到y(t)所表示的系统输出变量的影响。//Ifunexpecteddisturbancesactuponanopen-loopsystem,orifitsbehaviorisnotcompletelyunderstood,thentheoutputwillnotbehavepreciselyasexpected.如果有不期望的扰动作用在开环系统上,或者如果其行为不能完全掌握的话,则该系统的输出就不会完全如预期般动作。4:Finally,thecomputerinterpretsorunderstandswhattheimagerepresentsintermsofknowledgeaboutthesceneandgivestherobotasymbolicdescriptionofitsenvironment.最后,计算机能就场景的辨别,理解图像所表示的含义或作出解释,并使机器人用符号对环境的描述。5:Foreveryprocesstheremustbefinalactuatorthatregulatesthesupplyofenergyormaterialtotheprocessandchangesthemeasurementsignal.对每一过程,均必须由最终的控制器来调节过程中能量或材料的供给量,并且改变测量值。//Mostoftenthisisinsomekindofvalve,butitmightalsobeabeltormotorspeed,louverposition,andsoon.最常见的是由某种阀6来完成,但这也可能是一条皮带,或者是马达速度,口径位置等等。6:Forexample,manytransducershavevariableresistancewhichmustbeconvertedtoavoltagebyaspecialcircuit.举例来说,许多传感器具有电阻变换,这必须由一专门电路转换成电压。//Thisprocessofconvertingthetransduceroutputintoavoltagesignalwhichcanbeconnectedtotherestofthesystemiscalledsignalconditioning.这种将传感器输出转换成电压信号,并与系统的其它电路相连接的过程,称为信号调整。7:Fornegativefeedbacktoexist,eitherAorBmustbeanegativequantitytogivetheloopphaseinversion,andthereturndifferenceisalways(1+AB)fornegativefeedback.为了形成反馈,A或B必须为负量以使得环路形成倒向,因而对于负反馈深度恒等于(1+ab).H:1:However,thisadvantageismorethanoutweighedbythedisadvantagesofopen-loopcontrolandtheinherentadvantagesoffeedbacksystems.然而,这一优点比不上开环控制的缺点和反馈系统的固有优点。//First,inmanycasestheimplementationoftheopen
本文标题:上海电力学院自动化专业英语句子
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