《轮机英语（二三管轮）》-Lesson 29 Theory of Automatic Control

MarineElectricalSystemandAutomatizationLesson29

BasicTheoryofAutomaticControl

第29课自动控制基本理论LearningObjectives:1.Graspsomeusefulwordsandexpressionsinthewholetext.2.Afterstudyingthelesson,heorshewillhaveabetterunderstandingofBasicTheoryofAutomaticControl

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NewWordsandExpressions4part2

TextAnalysisL29TheoryofAutomaticControlTocontroladeviceorsystemistobeabletoadjustorvarytheparameterswhichaffectit.#对一个设备的控制就是调节或改变影响它的参数。L29TheoryofAutomaticControlThiscanbeachievedmanuallyorautomatically,dependinguponthearrangementsmadeinthesystem.#这可由手动实现，也可自动完成，取决于系统的布置。L29TheoryofAutomaticControlAllformsofcontrolcanbeconsideredtoactinaloop.#所有控制形式可看作在一回路发生作用。L29TheoryofAutomaticControlThebasicelementspresentintheloopareadetector,acomparatorandaregulator,allofwhichsurroundtheprocessandformtheloop.#组成回路的基本元件是传感器，比较器和调节器，它们均围绕处理过程，组成控制回路(图29-a)。L29TheoryofAutomaticControlThisarrangementisanautomaticclosedloopiftheelementsaredirectlyconnectedtooneanotherandthecontrolactiontakesplacewithouthumaninvolvement.#若各元件依次相连，则组成自动闭环控制，控制作用无人干预。L29TheoryofAutomaticControlAmanualclosedloopwouldexistifoneelementwerereplacedbyahumanoperator.如某一元件由人工代替，则为手动闭环控制。L29TheoryofAutomaticControlItcanbeseenthereforethatinaclosedloopcontrolsystemthecontrolactionisdependentontheoutput.#由此可见，在闭环控制系统中，控制作用依赖于系统输出。L29TheoryofAutomaticControlAdetectingormeasuringclementwillobtainasignalrelatedtothisoutputwhichisfedbacktothetransmitter.Fromthetransmitterthesignalisthenpassedtoacomparator.#检测元件或测量元件能获得与输出有关的信号，该信号传给变送器，之后传送到比较器。L29TheoryofAutomaticControlThecomparatorwillcontainsomesetordesiredvalueofthecontrolledconditionwhichiscomparedtothemeasuredvaluesignal.#比较器包含某个控制状态的设定值或给定值，并将该值与测量信号比较。L29TheoryofAutomaticControlAnydeviationordifferencebetweenthetwovalueswill

resultinanoutputsignaltothecontroller.#两者间的任何偏差或不同将产生输出信号给控制器。L29TheoryofAutomaticControlThecontrollerwillthentakeactioninamannerrelatedtothedeviationandprovideasignaltoaregulatingunit.#控制器以与偏差有关的方式进行调节，并为调节单元(执行机构)提供信号。L29TheoryofAutomaticControlTheregulatingunitwillthenincreasesordecreaseitseffectonthesystemtoachievethedesiredvalueofthesystemvariable.ThismoreinvolvedcontrolloopisshowninFig.29-1(b).#调节单元(执行机构)就会增加或减少对系统的控制作用，以实现系统的变量的要求值。更复杂的控制回路见图29-1(b)。L29TheoryofAutomaticControlThetransmitter,controllerandregulatingunitaresuppliedwithanoperatingmediuminordertofunction.#变送器，控制器和调节单元(执行机构)都采用某种工作介质，以完成其功能。L29TheoryofAutomaticControlTheoperatingmediummaybecompressedair,hydraulicoilorelectricity.#工作介质可以是压缩空气，液压油或电。L29TheoryofAutomaticControlForeachmediumvarioustypesoftransmittingdevices,controllersandregulatingunitsareused.#对每种介质，均有不同的传感器、调节器和执行机构。L29TheoryofAutomaticControlSomeofthetermsincommonuseincontrolsystemwillnowbedefined.#一些控制系统常用的术语被定义。L29TheoryofAutomaticControlOpenloopcontrolsystem开环控制系统Itisoneinwhichthecontrolactionisindependentoftheoutput,thatis,theoutputinnowaycontrolsthesystem.#开环控制系统是指控制作用不取决于输出，即输出决不对系统起作用。L29TheoryofAutomaticControlThisformofcontrolcanbeused,andhasbeenused,onsomeaccommodationheatingsystems.#这种控制形式能用于且已用于住舱的取暖系统。L29TheoryofAutomaticControlThequantityofsteamflowingthroughtheheatersiscontrolledbyavalve,thesettingofwhichisdeterminedbythedecktemperature.#通过加热器的蒸汽流量是由一个阀控制的，其设定值是由甲板温度来确定。L29TheoryofAutomaticControlAslongasthistemperatureremainsconstant,sowilltheheattotheairandtotheaccommodation.#只要此温度保持稳定，空气和住舱的加热也保持稳定。L29TheoryofAutomaticControlHowever,ifthesteamflow(orthesteampressure)changestheaircouldbecomecoolerorhotter.Butthesteamvalvewouldremaininthesamepositionasithasnofeedbackofinformationontheairtemperature.#然而，如果蒸汽流量(或蒸汽压力)改变时，供风会变得更冷或更热。可是蒸汽阀仍处于同一位置，因为它没有空气温度的反馈信息。L29TheoryofAutomaticControlFeedback反馈Thisisthetransmissionofasignalrepresentingtheoutput,i.e.thecontrolledcondition,forcomparisonwiththeinputtothesystem.#反馈是指传递一个反映输出大小的信号，即控制状态的信号，用于与系统的输入信号相比较。L29TheoryofAutomaticControlFeedbackwillincreaseaccuracy.#反馈会增加（调节的）精确度。L29TheoryofAutomaticControlClosedloopcontrolsystem

闭环控制系统Itisoneinwhichthecontrolactionisdependentontheoutput.#闭环控制系统是指控制作用取决于输出。L29TheoryofAutomaticControlThemarineexamplesaresteeringgear,boilercontrol,cargocontrol,enginecontrol,etc.#船用的例子有舵机和锅炉的控制、甲板货物的控制，柴油机的控制等等。L29TheoryofAutomaticControlThemeasuredvalueoftheoutputisbeingfedbacktothecontrollerwhichcomparesthisvaluewiththedesiredvalueforthecontrolledconditionandproducesanoutputtoalterthecontrolledconditionifthereisanydeviationbetweenthevalues.#测量出来的输出值反馈至控制器，控制器将此值与控制系统的给定值相比较，如果两者间有任何偏差，即产生输出信号来改变控制状态。L29TheoryofAutomaticControlMeasuredvalue测量值Actualvalueofthecontrolledcondition.#控制状态的实际数值。L29TheoryofAutomaticControlDesiredvalue给定值Thevalueofthecontrolledconditionthattheoperatordesirestoobtain.#操作者想获得的控制状态的数值。L29TheoryofAutomaticControlSetvalue设定值Thevalueofthecontrolledconditiontowhichthecomparingelementisset.Itisusuallythedesiredvalue.#控制状态相应单元所设定的值。通常就是给定值。L29TheoryofAutomaticControlDeviation偏差Itisthedifferencebetweenmeasuredanddesiredvalues.#指测量值与给定值之间的差异。L29TheoryofAutomaticControlThissignal,probablyconvertedintosomesuitableformsuchasvoltagetohydraulicoutputorvoltagetopneumaticoutputetc.,

wouldbeusedtoinstigatecorrectiveaction-objecttoreducetheerrortozero.#此信号可能会转化成某一合适的形式。例如：液压输出对应的电压值，或气压输出对应的电压值等，该信号将用于激发矫正动作—目标是将偏差减少至零。L29TheoryofAutomaticControlOffset剩余偏差Itissustaineddeviation(orerror).#指持续的偏差或差异。L29TheoryofAutomaticControlTransmitter(ortransducer)变送器Itchangesthesignalreceivedfromthedetector/sensorintosomereadilyamplifiedoutput,usuallyelectrical.#变送器将从检测器或传感器所得到的信号转变为容易放大的输出，通常是电。L29TheoryofAutomaticControlThetermtransmitterhasnowgeneralapplicationandisnolongerconfinedtoelectricalterminology,itcouldbemechanicalmovementtoelectricaloutputortopneumaticallyoutputandsoon.#变送器这一术语现在已经通用了，不再仅限于电气的术语，它可以是由电输出或气压输出等等而产生的机械运动。part3

Exercise&ExaminationInapneumaticautomationsystem,aunitproducingasignaltogovernthepositionofthecontrollerofthemeasuredvariable,relativetothevalueofthemeasuredvariable,issaidtohave_____.A.resetaction B.proportionalactionC.twopositionactionD.rateactionThevalueofthecontrolledvariable,whichunderanyfixedsetofconditionstheautomaticcontrolleroperatestomaintain,isknownas_____.

A.setpointB.controlpointC.deviationD.offsetInanautomatedcontrolsystem,whichofthefollowingstatementswouldapplytoanytypeofclosedloopsystem?

A.Themanipulatedvariabl