过程控制第4章演示文稿课件

ChapterfourConnectionofpartsofacontrolsystem

andthe“setting”ofacontroller§4.1Introduction§4.2Connectionofpartsofacontrolsystem§4.3Objectiveoftuningthecontroller§4.4TuningwaysChapterfourConnectionofp1Controllerdesigninvolvestheselectionofthecontrolmodestobeusedandthedeterminationofthevaluesofparametersofeachmode.Forcontinuoussystems,theproportionalmodeisusuallycombinedwiththeintegraland/orderivativemodestoformPI,PDandPIDcontroller.Theparametersforthreemodesaretheproportionalgain(),theintegraltime(),andthederivativetimeconstant().§4.1IntroductionControllerdesigninvolvesthe2Whentheappropriatecontrolmodehasbeenchosenforthegivencontrollerinacontrolsystem,thetwo-thirdsisonlycompletedinthetaskofthecontrolsystemdesign.Thefinalpartofthetakeistoconnectthepartsoftheconstitutepartsofacontrolsystemtogetherfortoformacompletelycontrolsystemandchosethevalueoftheparameters,theproportionalgain(),theintegraltime(),andthederivativetimeconstant(),ofthecontrolmodeschoseninthecontroller.Whentheappropriatecontrolm3ThesimplestdesignmethodistospecifyaPIDcontrollerandthendeterminethecontrolmodeparametersinthefieldduringstart-up.Thisfieldadjustmentiscalled“settingthecontroller”,andaprocedurecalledtheultimatecyclemethodisusedtodeterminethemodeparameters.Thesimplestdesignmethodis4§4.2Connectionofpartsofacontrolsystem

Aclosed-loopfeedbackcontrolsystemmustbeanegativefeedbackcontrolsystem.Forobtaininganegativefeedbackcontrolsystem,weoughttoelectcorrectlyeveryelementconstructingacontrolsystem.§4.2Connectionofpartsofa5§4.1.1ThesymbolruleofeveryelementconstructingacontrolsystemWhenconnectingeveryelementandformingacontrolsystem,wemustnotetheactionwayofeveryelementconstructingthecontrolsystem.Theactionwayofeveryelementhasusuallytwobasictypes,suchastheair-to-openorair-to-closeofavalve,thedirect-actionorreverse-actionofacontrollerandapositiveornegativeobjectandsoon.Theactionwayofeveryelementisdescribedwithasymbolrule.§4.1.1Thesymbolruleofever61.Controller

Therearetwoactionwaysincontrollersusually,thedirectactionwaycontrollerandthereverseactionway.Whenthealgebravalueoftheinputsignal,theerrorsignal,enlargingandthealgebravalueoftheoutputsignal,thecontrolsignal,enlargesimmediatelyinacontroller,thecontrolleristhedirectactioncontroller.Thedirectwayofcontrollerisdescribedwiththesymbolofpositive,“+”.Whenthealgebravalueoftheinputsignalenlargingandthealgebravalueoftheoutputsignaldecreasesimmediatelyinacontroller,thecontrollerisreverseactioncontroller.thereverseactionwayofcontrollerisdescribedwiththesymbolofnegative,“―”.1.ControllerTherearetwoac72.ControlvalveormanipulatingelementTherearetwoactionwaysinmanipulatingelementsusually,thedirectactionwayandthereverseactionway.Whenthealgebravalueoftheinputsignal,thecontrolsignal,enlarging,andthealgebravalueoftheoutputsignal,themanipulatingvariable,enlargesimmediatelyinamanipulatingelement,themanipulatingelementisthedirectactionmanipulatingelement.Thedirectwayofmanipulatingelementisdescribedwiththesymbolofpositive,“+”.2.Controlvalveormanipul8Whenthealgebravalueoftheinputsignaldecreasingandthealgebravalueoftheoutputsignaldecreasesimmediatelyinmanipulatingelement,themanipulatingelementisreverseactionmanipulatingelement.Thereverseactionwayofmanipulatingelementisdescribedwiththesymbolofnegative,“―”Incontrolvalves,therearetwotypesoftheair-to-openandair-to-closevalve.Theactionwayofair-to-openisdescribedwiththesymbolofpositive,“+”,andtheactionwayofair-to-closeisdescribedwiththesymbolofnegative,“―”.Whenthealgebravalueofthe93.Processorcontrolledelement

Therearetwotypesinprocessesorelementsusually,thepositiveprocessorelementandthenegativeprocessorelement.Whenthealgebravalueofthecontrolledvariableinaprocessorcontrolledelementincreasesfollowingittoincreaseimmediatelyforthequantityofenergyorqualityflowingintoaprocessorcontrolledelement,theprocessorcontrolledelementisthepositiveanddescribedwiththesymbolofpositive,“+”.Contrarilytheprocessorcontrolledelementisnegativeanddescribedwiththesymbolofpositive,“―”.3.Processorcontrolledelem104.MeasuringelementTherearetwoactionwaysinMeasuringelementsusually,thedirectactionwayandthereverseactionway.Whenthealgebravalueoftheinputsignal,thecontrolledvariable,enlargingandthealgebravalueoftheoutputsignal,themeasuringvalue,enlargesimmediatelyinameasuringelement,themeasuringelementisthedirectactionmeasuringelement.Thedirectwayofmeasuringelementisdescribedwiththesymbolofpositive,“+”.4.MeasuringelementTherear11Whenthealgebravalueoftheinputsignaldecreasingandthealgebravalueoftheoutputsignaldecreasesimmediatelyinmeasuringelement,themeasuringelementisreverseactionmeasuringelement.Thereverseactionwayofmeasuringelementisdescribedwiththesymbolofnegative,“―”.Whenthealgebravalueofthe12§4.1.2Criteriaequationofsymbolrule(controller“±”)·(manipulatingelement“±”)·(process“±”)·(measuringelement“±”)=“－”Notice:

Thisequationismainlyusedtodeterminetheactionwayofacontroller,becausethesymbolofaprocessliesonimpersonalprocessandtheactionwayofamanipulatingelementliesonthesecurityofaprocessandmeasuringelementisgenerallypositive.§4.1.2Criteriaequationofsy13Whentheprocessispositiveandthevalveinstalledisanair-to-openinasystem,thecontrollermustbeadirectactionwaycontroller.Inotherwords,whenthesymboloftheprocessissamewiththesymbolofthevalveinacontrolsystem,thesymbolofthecontrollermustbe“－”.Whereasthesymboloftheprocessisreversewoththesymbolofthevalve,thesymbolofthecontrolleris“+”.Whentheprocessispositivea14§4.3Objectiveofsettingthecontroller

Ⅰ.Objective:Theobjectiveof“settingthecontroller”isthatwemustchoosepropervalueoftheparametersofthecontrolmodesemployedbythecontrolleraftertheconnectionofacontrolsystemcompletedinordertoobtainastablecontrolsystemandthehighercontrolqualitythatmeetsthecontrolobjectives.§4.3Objectiveofsettingthe15Thecontrolobjectivesmayspecifysomeorallofthefollowingcharacteristics:

1.

Theaccuracyandspeedofresponseofthemeasuringtransmitter;

2.

Theresidualerrorallowedbythecontrollerafteraloadchange;

3.Theresponseofthecontrolsystemtoastepchangeinloadorsetpoint.Quarteramplitudedecayorcriticaldampingmaybespecified;

4.Themaximumfrequencylimit.Thecontrolsystemisabletofollowsetpointchangesanddisturbanceswithfrequencieslessthanthemaximumlimit;Thecontrolobjectivesmay165.Theresponsetime,therisetime,andthesettlingtimeofthecontrolsystem;6.Minimumcost.Theinitialcostofthehardwareisonlyonepartofthisobjective.Maintenancecost,operatingcost,rejectproductcosts,andenvironmentalcostsareexamplesoftheothercoststhatmaybeafactor.Thisobjectiverequiresajudgmentbasedoneconomicandsocialconditions.Intuningthecontroller,theobjectiveofthechoiceparametersistochoosethereasonablecontrollerparameterstomakecontrollercanattainabovepartorallofcontroltargetincontrolprocess.5.Theresponsetime,theris17Ⅱ.StableMarginAcontrolsystemnotonlyisstablebutalsohasthestablemargin.Thestablemarginofacontrolsystemisdescribedbyξandψwhicharethedamp-coefficientanddecay-ratioofacontrolsystem.Assume,thereisastableoscillatingfunction:,While:decayratio:

ψ=.Where:themisthedecayexponent,m=α/ω.

Ⅱ.StableMarginAcontrolsyst18Theαistherealpartandtheωistheimaginativepartinapairconjugatecomplexroot.Theαistherealpartandtheωistheimaginativepartinapairconjugatecomplexroot.Thisshowsthatthegreatertheαis,thegreaterthemis.Inotherwords,thegreaterthemis(ortheαis),thequickerthedecay-functiondecays.Thustherateofdecayspeedindecayresponseprocesscanbedescribedwiththeα.Theαistherealpartandthe19Theωisoscillatingdecayfrequencyofthedecayfunction.Becausethegreateroscillatingfrequency,theω,cancausethattheactionoftheactuatorisfrequently,theωisnotthegreatervalue.Theωisoscillatingdecayfre20Intherootcomplexplane,wemaydrawsomelinestoformthecertaindistrictlimited,asaboveFigure,whichistheobjectivedistrictinthattheclosed-loopcharacteristicrootsofthecontrolsystemtunedshouldsitthrough“settingthecontroller”course.Theobjectivedistrictrepresentedtherequesttothecontrolsystem.Intherootcomplexplane,we21Inthefigure,theequal-αlinerepresentsthequicknessofacontrolsysteminregulatingcourse,allofcontrolsystemshavethesamequickness,whichhavetheclosed-loopcharacteristicrootsattheequal-αline,andtheequal-ωlinerepresentsthemosthighoscillating-frequencyinthetransientofacontrolsystem,allofcontrolsystemshavethemosthighoscillating-frequency,whichhavetheclosed-loopcharacteristicrootsattheequal-ωline,andtheequal-mlinerepresentsthedecay-rateinthetransientofacontrolsystem,allofcontrolsystemshavethesamedecay-rateinthetransient,whichhavetheclosed-loopcharacteristicrootsattheequal-mline.Inthefigure,theequal-αlin22§4.4Tuningways§4.3.1Theexperienceway

parameterrangcontrolsystemδ(%)(min)(min)liquid-levelpressureflow-ratetemperature20~80%30~70%40~100%20~60%3~100.1~10.4~30.3~1－－－§4.4Tuningways§4.3.1Theex23Theexperiencewayismethodbasedondesigner’experienceofcontrolsystem.Takingvaluerangofthreecontrolparametersislistedinabovetableinvarioustypesofcontrolsystems.Takingvaluerangisabasistomakeexperiencemethodestablisheseverykindofcontrolparameter.

Notice:Inthetable,theproportionalcontrolactionisdescribedwiththeparameter,δ.δis

calledtheproportional-bandandequal:δ=1/.Fromherethen,thesmallerthevalueofδis,thestrongertheproportionalcontrolactionis.Theexperiencewayismethodb24Thestepsoftheexperiencemethodare:1.

ThePcontroller:

2.ThePIcontroller:

δ

80%;∞(cancelingtheintegralcontrolmode);0(cancelingthederivativecontrolmode).

Then:δGraduallyincreasingψ=4:1(Quarteramplitudedecayresponsecourse).δagain

increasing

20%;0(cancelingthederivativecontrolmode).

Then:

takinggratervalue

Graduallydecreasing

ψ=4:1(Quarteramplitudedecayresponsecourse).Thestepsoftheexperienceme25

3.ThePIDcontroller:

δagain

decreasing(10~20)%;maintaining

thevalue;

Then:

0

Graduallyincreasingψ=4:1(Quarteramplitudedecayresponsecourse).

3.ThePIDcontroller:δ26§4.3.2CriticalProportional-DegreeWay(orStableBoundaryWay)Incriticalproportional-degreeway,tosetvariouscontrolparametersisbasedonthecriticalproportional-degreeandthecriticalequal-amplitudeoscillatingcyclewhenthetransientofacontrolsystemiscriticaloscillatory.parameterrangControlmodeProportionalmodePProportionalPlusIntegralPIProportionalplusDerivativeplusIntegralPID22.21.78

δ(min)(min)0.850.50.13－－－§4.3.2CriticalProportional-D27Thestepsofcriticalproportional-degreeway:1.Whenaprocessisstable,thecontrolsystemtunedistakenfrommanual-controlstateintoautomatic-controlstate.Theδshouldisthegreatervalue;2.Thenthevalueofδgraduallydecreases.(Oscillationgraduallyaggrandizes);3.Then,tochangethesetpoint-valuewithstepchange.(Thechangerangofthestepchangeapproximatelyequalthe10~30%ofthestablevalueofaprocess.);Thestepsofcriticalproporti284.Toobservetheresponseofcontrolledvariableofthecontrolsystemandrecordchangevalueofthecontrolledvariableandthevalueofδ,andthentodeterminewhetherthetransientofthecontrolsystemistheequal-amplitudeoscillatingaccordingtothedatesrecorded.Ifthetransientofthesystemisnotequal-amplitudeoscillatingone,wemustrepeatthesteps(2)and(3)untiltheequal-amplitudeoscillatingtransientappears;5.Whentheequal-amplitudeoscillatingtransientappears,thevalueofδthenisthe,andtheperiodofoscillationisthe;4.Toobservetheresponseof296.Wecandeterminethevalueofthreecontrolparameterscorrespondingtoeachcontrolmodeaccordingtothetablex.xxandthevalueoftheandacquiredthroughtheabovetest.6.Wecandeterminethevalue30§4.3.3DecayResponseGraphWay

Indecayresponsegraphway,tosetvariouscontrolparametersisbasedonthequarteramplitudedecayoscillationproportional-degreeandthequarteramplitudedecayoscillatingcyclewhenthetransientofacontrolsystemisthequarteramplitudedecayoscillatingresponse.§4.3.3DecayResponseGraphWa31ProportionalPlusIntegralPIProportionalplusDerivativeplusIntegralPID22.21.780.850.50.13

δ(min)(min)－－－ParameterrangcontrolmodeProportionalPProportionalProportionalpl32Thestepsofdecayresponsegraphway:1.Whenaprocessisstable,thecontrolsystemtunedistakenfrommanual-controlstateintoautomatic-controlstate.Theδ

shouldisthegreatervalue;2.Then,tochangethesetpoint-valuewithstepchange.(Thechangerangofthestepchangeapproximatelyequalthe10~30%ofthestablevalueofaprocess.);3.Thenthevalueofδgraduallydecreases.(Oscillationgraduallyaggrandizes);Thestepsofdecayresponsegr334.Toobservetheresponseofcontrolledvariableofthecontrolsystemandrecordchangevalueofthecontrolledvariableandthevalueofδ,andthentodeterminewhetherthetransientofthecontrolsystemisthequarter-amplitudedecayoscillatoryaccordingtothedatesrecorded.Ifthetransientofthesystemisnotquarter-amplitudedecayoscillatingone,wemustrepeatthesteps(2)and(3)untilthequarter-amplitudedecayoscillatingtransientappears;5.Whenthequarter-amplitudedecayoscillatingtransientappears,thevalueofδthenisthe,andtheperiodofoscillationisthe;4.Toobservetheresponseof34

6.Wecandeterminethevalueofthreecontrolparameterscorrespondingtoeachcontrolmodeaccordingtoabovetableandthevalueoftheandacquiredthroughtheabovetest.6.Wecandeterminethevalue354.3.4dynamiccharacteristicparametersmethodTheso-calleddynamicstatecharacteristicparametermethod,itisthemethodinwhichtheoptimumcontrolparameterofacontrollerischosenthroughasetofempiricalformulasaccordingasthestep-responseofthecontrol-channelofthebroadsenseopen-processinacontrolsystem.ThewayhasbeenbroughtbyZieglerandNicholsat1942year4.3.4dynamiccharacteristic36

Wc(S)

Wv(S)

Wo(S)

Wm(S)SPYThereisaclosed-loopcontrolsystemshowedinfigure.Atinputpotsofmanipulating-elementandmeasuring-transmittertobreakconjunctionofthesystem,wearebringtobearastep-signalattheinputpotsofmanipulating-elementandmeasureandrecordtheoutputsignalofthemeasuring-transmitterinthecontrolsystem.Wc(S)Wv(S)Wo(S)Wm(S)SPYThe37Accordingtothesedataoftheoutput-signalobtained,wedrawthestep-responsecharacteristiccurve,andfindoutthecharacteristicparametersoftheprocess,-timedelay,-timeconstant,and-responsespeedbasingonthestep-responsecharacteristiccurve.ThusAccordingtothecharacteristicparametersoftheprocessobtained,wemaycalculatetheoptimumsettingcontrolparametersofacontrollerbasingontheformulaslistedbelow.Accordingtothesedataofthe381.Non-regulatingprocessWhenabroadsenseopen-processisanon-regulatingprocess,ofwhichstep-responsecurveisillustratedinthefollowingfigure,wemayusethesettingformulaslistedinthetable1tocalculatethesetting-parametersofacontroller.t0y(t)=tg0tx(t)1.Non-regulatingprocessWhen39Thematchingtransferfunctionofanon-regulatingprocessis:（1）（2）Whenthereisaobvioustime-delayinaprocess,(including),thetransferfunctionis:Thematchingtransferfunct40Table1=0.75,settingformulas

0,5

20.85

3.3

1.1W(S)(controller)ControlmodePPIPIDTable1=0.75,set412.Self-regulatingprocessWhenabroadsenseopen-processisaself-regulatingprocess,ofwhichstep-responsecurveisillustratedinthefollowingfigure,wemayusethesettingformulaslistedinthetable2tocalculatethesetting-parametersofacontroller.0tx(t)t0y(t)2.Self-regulatingprocessWhen42ControlmodeW(S)(controller)

1.13.3

0.8520.5

PIDPIPTable2=0.75,settingformulasW(S)PIDPIPTable243ChapterfourConnectionofpartsofacontrolsystem

andthe“setting”ofacontroller§4.1Introduction§4.2Connectionofpartsofacontrolsystem§4.3Objectiveoftuningthecontroller§4.4TuningwaysChapterfourConnectionofp44Controllerdesigninvolvestheselectionofthecontrolmodestobeusedandthedeterminationofthevaluesofparametersofeachmode.Forcontinuoussystems,theproportionalmodeisusuallycombinedwiththeintegraland/orderivativemodestoformPI,PDandPIDcontroller.Theparametersforthreemodesaretheproportionalgain(),theintegraltime(),andthederivativetimeconstant().§4.1IntroductionControllerdesigninvolvesthe45Whentheappropriatecontrolmodehasbeenchosenforthegivencontrollerinacontrolsystem,thetwo-thirdsisonlycompletedinthetaskofthecontrolsystemdesign.Thefinalpartofthetakeistoconnectthepartsoftheconstitutepartsofacontrolsystemtogetherfortoformacompletelycontrolsystemandchosethevalueoftheparameters,theproportionalgain(),theintegraltime(),andthederivativetimeconstant(),ofthecontrolmodeschoseninthecontroller.Whentheappropriatecontrolm46ThesimplestdesignmethodistospecifyaPIDcontrollerandthendeterminethecontrolmodeparametersinthefieldduringstart-up.Thisfieldadjustmentiscalled“settingthecontroller”,andaprocedurecalledtheultimatecyclemethodisusedtodeterminethemodeparameters.Thesimplestdesignmethodis47§4.2Connectionofpartsofacontrolsystem

Aclosed-loopfeedbackcontrolsystemmustbeanegativefeedbackcontrolsystem.Forobtaininganegativefeedbackcontrolsystem,weoughttoelectcorrectlyeveryelementconstructingacontrolsystem.§4.2Connectionofpartsofa48§4.1.1ThesymbolruleofeveryelementconstructingacontrolsystemWhenconnectingeveryelementandformingacontrolsystem,wemustnotetheactionwayofeveryelementconstructingthecontrolsystem.Theactionwayofeveryelementhasusuallytwobasictypes,suchastheair-to-openorair-to-closeofavalve,thedirect-actionorreverse-actionofacontrollerandapositiveornegativeobjectandsoon.Theactionwayofeveryelementisdescribedwithasymbolrule.§4.1.1Thesymbolruleofever491.Controller

Therearetwoactionwaysincontrollersusually,thedirectactionwaycontrollerandthereverseactionway.Whenthealgebravalueoftheinputsignal,theerrorsignal,enlargingandthealgebravalueoftheoutputsignal,thecontrolsignal,enlargesimmediatelyinacontroller,thecontrolleristhedirectactioncontroller.Thedirectwayofcontrollerisdescribedwiththesymbolofpositive,“+”.Whenthealgebravalueoftheinputsignalenlargingandthealgebravalueoftheoutputsignaldecreasesimmediatelyinacontroller,thecontrollerisreverseactioncontroller.thereverseactionwayofcontrollerisdescribedwiththesymbolofnegative,“―”.1.ControllerTherearetwoac502.ControlvalveormanipulatingelementTherearetwoactionwaysinmanipulatingelementsusually,thedirectactionwayandthereverseactionway.Whenthealgebravalueoftheinputsignal,thecontrolsignal,enlarging,andthealgebravalueoftheoutputsignal,themanipulatingvariable,enlargesimmediatelyinamanipulatingelement,themanipulatingelementisthedirectactionmanipulatingelement.Thedirectwayofmanipulatingelementisdescribedwiththesymbolofpositive,“+”.2.Controlvalveormanipul51Whenthealgebravalueoftheinputsignaldecreasingandthealgebravalueoftheoutputsignaldecreasesimmediatelyinmanipulatingelement,themanipulatingelementisreverseactionmanipulatingelement.Thereverseactionwayofmanipulatingelementisdescribedwiththesymbolofnegative,“―”Incontrolvalves,therearetwotypesoftheair-to-openandair-to-closevalve.Theactionwayofair-to-openisdescribedwiththesymbolofpositive,“+”,andtheactionwayofair-to-closeisdescribedwiththesymbolofnegative,“―”.Whenthealgebravalueofthe523.Processorcontrolledelement

Therearetwotypesinprocessesorelementsusually,thepositiveprocessorelementandthenegativeprocessorelement.Whenthealgebravalueofthecontrolledvariableinaprocessorcontrolledelementincreasesfollowingittoincreaseimmediatelyforthequantityofenergyorqualityflowingintoaprocessorcontrolledelement,theprocessorcontrolledelementisthepositiveanddescribedwiththesymbolofpositive,“+”.Contrarilytheprocessorcontrolledelementisnegativeanddescribedwiththesymbolofpositive,“―”.3.Processorcontrolledelem534.MeasuringelementTherearetwoactionwaysinMeasuringelementsusually,thedirectactionwayandthereverseactionway.Whenthealgebravalueoftheinputsignal,thecontrolledvariable,enlargingandthealgebravalueoftheoutputsignal,themeasuringvalue,enlargesimmediatelyinameasuringelement,themeasuringelementisthedirectactionmeasuringelement.Thedirectwayofmeasuringelementisdescribedwiththesymbolofpositive,“+”.4.MeasuringelementTherear54Whenthealgebravalueoftheinputsignaldecreasingandthealgebravalueoftheoutputsignaldecreasesimmediatelyinmeasuringelement,themeasuringelementisreverseactionmeasuringelement.Thereverseactionwayofmeasuringelementisdescribedwiththesymbolofnegative,“―”.Whenthealgebravalueofthe55§4.1.2Criteriaequationofsymbolrule(controller“±”)·(manipulatingelement“±”)·(process“±”)·(measuringelement“±”)=“－”Notice:

Thisequationismainlyusedtodeterminetheactionwayofacontroller,becausethesymbolofaprocessliesonimpersonalprocessandtheactionwayofamanipulatingelementliesonthesecurityofaprocessandmeasuringelementisgenerallypositive.§4.1.2Criteriaequationofsy56Whentheprocessispositiveandthevalveinstalledisanair-to-openinasystem,thecontrollermustbeadirectactionwaycontroller.Inotherwords,whenthesymboloftheprocessissamewiththesymbolofthevalveinacontrolsystem,thesymbolofthecontrollermustbe“－”.Whereasthesymboloftheprocessisreversewoththesymbolofthevalve,thesymbolofthecontrolleris“+”.Whentheprocessispositivea57§4.3Objectiveofsettingthecontroller

Ⅰ.Objective:Theobjectiveof“settingthecontroller”isthatwemustchoosepropervalueoftheparametersofthecontrolmodesemployedbythecontrolleraftertheconnectionofacontrolsystemcompletedinordertoobtainastablecontrolsystemandthehighercontrolqualitythatmeetsthecontrolobjectives.§4.3Objectiveofsettingthe58Thecontrolobjectivesmayspecifysomeorallofthefollowingcharacteristics:

1.

Theaccuracyandspeedofresponseofthemeasuringtransmitter;

2.

Theresidualerrorallowedbythecontrollerafteraloadchange;

3.Theresponseofthecontrolsystemtoastepchangeinloadorsetpoint.Quarteramplitudedecayorcriticaldampingmaybespecified;

4.Themaximumfrequencylimit.Thecontrolsystemisabletofollowsetpointchangesanddisturbanceswithfrequencieslessthanthemaximumlimit;Thecontrolobjectivesmay595.Theresponsetime,therisetime,andthesettlingtimeofthecontrolsystem;6.Minimumcost.Theinitialcostofthehardwareisonlyonepartofthisobjective.Maintenancecost,operatingcost,rejectproductcosts,andenvironmentalcostsareexamplesoftheothercoststhatmaybeafactor.Thisobjectiverequiresajudgmentbasedoneconomicandsocialconditions.Intuningthecontroller,theobjectiveofthechoiceparametersistochoosethereasonablecontrollerparameterstomakecontrollercanattainabovepartorallofcontroltargetincontrolprocess.5.Theresponsetime,theris60Ⅱ.StableMarginAcontrolsystemnotonlyisstablebutalsohasthestablemargin.Thestablemarginofacontrolsystemisdescribedbyξandψwhicharethedamp-coefficientanddecay