Здравина

Въведение

Inactualproblems,theperturbationofsystemcharacteristicsorparametersisofteninevitable.Therearetwomainreasonsfortheperturbation:oneisduetoinaccuratemeasurementTheactualvalueofthecharacteristicorparameterwilldeviatefromitsdesignvalue(nominalvalue),andtheotheristheslowdriftofthecharacteristicorparametercausedbytheinfluenceofenvironmentalfactorsduringtheoperationofthesystem.

Currentresearchonrobustnessismainlylimitedtolinearsteadycontrolsystems,andtheissuesinvolvedincludestability,nostaticerror,adaptivecontrol,etc.Therobustnessproblemiscloselyrelatedtotherelativestabilityofthecontrolsystem(aperformanceindexthatcharacterizesthestabilitymarginofthecontrolsysteminthefrequencydomain)andtheprincipleofinvariance(thetheoryofcontrollingandeliminatingtheinfluenceofdisturbancesonthecontrolsystemintheautomaticcontroltheory).Theestablishmentoftheinternalmodelprinciple(adesignprincipleofimplantingthedynamicmodelofexternallyactingsignalsintothecontrollertoformahigh-precisionfeedbackcontrolsystem)hasplayedanimportantroleintheresearchofrobustness.Earlyrobustcontrolfocusedonthesensitivityofsmallperturbationanalysis.Modernrobustcontrolfocusesontheanalysisanddesigntheoryandmethodsundernon-micro-boundedperturbationinthecontrolsystemandthenon-fragilecontrolmethodwithnon-micro-boundedperturbationinthecontroller.

Analysisanddesignmethodsofuncertainsystemsmustbeestablishedtomakethesystemrobust.Theuseoffeedbacktodesignarobustcontrolsystemisbasedonanincompletedescriptionofthecontrolledobject.Thisisdifferentfromthedesignofalinearmultivariablecontrolsystem,whichrequiresthemathematicalmodeloftheobjecttobeaccuratelyknowninadvance.

Класификация

Robustnessincludesstabilityrobustnessandqualityrobustness.Whetheracontrolsystemisrobustornotisthekeytoitsactualapplication.Therefore,thedesignofmoderncontrolsystemshastakenrobustnessasoneofthemostimportantdesignindicators.

Inordertosolvetherobustnessproblemofcontrolsystems,twomaindirectionshaveemergedinrecentyears:oneisactiveadaptationtechnology,whichiscommonlycalledadaptivecontrolsystemdesigntechnology.Itusesidentificationmethodstocontinuouslyunderstandtheuncertaintyofthesystem,andadjuststhestructureandparametersofthecontrolleronthisbasis,sothatthesystemmeetstheperformanceindexrequirements.Theotherispassiveadaptationtechnology,whichisgenerallycalledrobustcontrol.Designtechnology.Designacontrollerforthesystemwithuncertainty,sothatwhenthesystemworkswithintheuncertaintyrange,itcanmeetthedesignperformanceindexrequirementsofthesystem.

Therobustnessofthecontrolsystemreferstotheabilityofthesystemtokeepcertainperformanceunchangedunderthedisturbanceofuncertainty.Iftheuncertaintyoftheobjectcanbedescribedbyaset,examinecertainperformanceindicatorsofthecontrolsystem,suchasstabilityqualityindicators,etc.,anddesignacontroller.IfthecontrollercanmeetthegivenrequirementsforeachobjectintheobjectsetPerformanceindex,thecontrollerissaidtoberobusttothisperformanceindex(characteristic).Therefore,whentalkingaboutrobustness,acontrollermustberequired,asetofobjectsandcertainsystemperformance.Forthecontrolsystem,twoimportantconceptsofrobustnessare:

StableandrobustRobustness:AcontrollerisrobustandstableifitcanensurethestabilityofthesystemforeachobjectinthesetP.

Qualityrobustness:AcontrollerisconsideredtobequalityrobustifitcanensuresystemstabilityandaspecificqualityforeachobjectinthesetP.

Здрав контрол

Здрав контролisacontrollerdesignmethodthatfocusesonthereliabilityofcontrolalgorithms.Robustnessisgenerallydefinedastheminimumrequirementthatthecontrolsystemmustmeetinordertoensuresafetyintheactualenvironment.Oncethecontrollerisdesigned,itsparameterscannotbechangedandthecontrolperformanceisguaranteed.

Therobustcontrolmethodgenerallyassumestheinformationofthedynamiccharacteristicsoftheprocessanditsvariationrangeinthetimedomainorfrequencydomain.Somealgorithmsdonotrequireanaccurateprocessmodelbutsomeofflineidentification.Thedesignofgeneralrobustcontrolsystemisbasedonsomeworstcases,sothegeneralsystemdoesnotworkintheoptimalstate.

Therobustcontrolmethodissuitableforapplicationswherestabilityandreliabilityaretheprimarygoals.Atthesametime,thedynamiccharacteristicsoftheprocessareknownandtherangeofuncertainfactorscanbeestimated.Thecontrolofairplanesandspacevehiclesareexamplesofsuchsystems.Inprocesscontrolapplications,somecontrolsystemscanalsobedesignedwithrobustcontrolmethods,especiallyforthosethataremorecriticalandhave(1)awiderangeofuncertainfactors;(2)objectswithsmallstabilitymargins.

However,thedesignofarobustcontrolsystemmustbecompletedbyseniorexperts.Oncethedesignissuccessful,toomuchmanualinterventionisnotrequired.Ontheotherhand,ifyouwanttoupgradeormakemajoradjustments,thesystemmustberedesigned.

Usually,systemanalysismethodsandcontrollerdesignaremostlyestablishedbasedonmathematicalmodels,andvariousmethodshavebecomematureandperfect.However,therearealwaysuncertaintiesofonekindoranotherinthesystem.Whenmodelingthesystem,sometimesonlythesituationneartheoperatingpointisconsidered,resultinginartificialsimplificationofthemathematicalmodel;ontheotherhand,therearemanufacturingtolerancesbetweentheexecutivecomponentsandthecontrolcomponents,andthesystemoperationprocessalsohasaging,wear,andenvironmentandoperation.Deterioratingconditionsandotherphenomenamakemostsystemshaveuncertaintiesintheirstructureorparameters.Inthisway,theanalysisresultsofthesystemwithaccuratemathematicalmodelsorthedesignedcontrollersoftendonotmeettheengineeringrequirements.Inrecentyears,peoplehavecarriedoutresearchontherobustcontrolofuncertainsystems,andobtainedaseriesofresearchresults.Hoorobustcontroltheoryandμanalysistheoryarecurrentlyoneofthemostactiveresearchfieldsincontrolengineering,andhavebeenfavoredbycontrolresearchersformanyyears.Theauthorsystematicallystudiestherobuststabilityoflinearuncertainsystems,time-lagsystems,intervalsystems,anddiscrete-timesystems,andputsforwardtheanalysisanddesignmethodsoftherobuststabilityofthesystem.

Здрав контролsystemdesign

Therearemanywaystodesignarobustcontrolsystem,includingrootlocusmethod,frequencyresponsemethodandITAE.Thetwobasictasksofrobustcontrolsystemdesignaretodeterminethecontrollerstructureandadjustthecontrollerparameterstoobtainthe"optimal"systemperformance.Intheprocessofrobustcontrolsystemdesign,itisusuallyassumedthatthecontrolledobjecthasacomprehensiveUnderstandingisaprerequisite,andthecontrolledobjectisusuallydescribedbyalineartime-invariantcontinuousmodel.Thechoiceofthecontrollerstructureisgenerallybasedonthestartingpointthatthesystemresponsecanmeetacertainperformancecriterion.

Inmanyoccasions,theidealdesigngoalofthecontrolsystemisthatthesystemcanaccuratelyandtimelyreproducetheinput.Correspondingly,theBodediagramofthesystemshouldbeveryflat,thatis,ithasaninfinitebandwidthof0dBgainandthephaseangleisalways0.However,sinceanysystemcontainsinductiveorcapacitivecomponentsthatstoreenergy,thereisnosuchidealsysteminpractice.Theseenergystorageelementsandtheirconnectionwithenergy-consumingcomponentsdeterminethedynamiccharacteristicsofthesystem.Suchasystemcanreproducesomeinputsquiteaccurately,butcannotreproduceotherinputsatall,thatis,thebandwidthoftheactualsystemisalwayslimited.

Здрав дизайн

Whenoptimizingthedesignbymakingtheproductperformancereachthetargetvalueandreducingtheirdeviation,therobustdesigntechnologyusesbothtraditionalideasandnewThought.Thefollowingaresomeoftheseideas.

Загуба на функция

Thelossfunctionisaquadraticformulausedtoestimatethecostcausedbythedeviationofthemeanvaluefromthetargetvalueandproductperformance.Thiscostisbasedontheuser’sopinionTheeconomiclosscausedbyproductdefects.Thetraditionalmethodonlycalculatesthislosswhentheproductperformanceexceedstheuser'sspecificationrequirements.Therobustdesignmethodestimatesthislossonthebasisofthecurrentproductperformancedistribution(distributionnearthemeanvalue).

Ортогонален масив

Ортогонален масивhasseveraluniqueproperties.Theycanworkinseveralranges,butthemostcommonareintwoorthreeranges.Oneoftheirmostimportantpropertiesisbalance:whentherangeinonecolumnisconstant,allotherrangesintheothercolumnswillbeobtainedbyrotatingtheirvalues.Byusingthisbalanceofthearray,theinfluenceofeachfactorcanbeeffectivelydetermined.

Съотношение сигнал/шум

Thesignal-to-noiseratioisameasureoftheoutputperformancedeviationofarobustdesignexperiment.Thepurposeofthesignal-to-noiseratio(S/N)istoexpresstherepeatabilityoftheoutputperformanceasanumber.Thisnumbercanthenbetreatedinasimilarway,asinthecaseofbondingstrength,inordertoincreasethemeanvalue.

Здрав дизайнexperiment

Performingrobustdesignexperimentinvolvestheuseofmanyqualityengineeringtoolsmentionedearlier.Thesuccessofthisworkdependsonthecorrectselectionofteammembers,focusingonoptimizingandtestingappropriateperformance,andfollowingmethodologicalguidelines.Thestepsforasuccessfulrobustdesignexperimentareasfollows.

1.Problemdefinition.Thefirststepinconductingarobustdesignexperimentistooutlinetheobjectivesoftheexperimentanddefinetheprocessordesignperformancetobeoptimized.However,onlyoneperformancecanbeoptimizedatatime,andmanyperformancescanbemeasuredduringexperimentsandthenanalyzedseparately.Thefinalparameterselectionisamixtureofvariousrecommendedparameters,whichdependsonthecompromiseofdifferenttargetsforeachtargetperformancelevel.

Itisimportanttogeneratetheboundariesoftheproductordesigntobeoptimized.Theexperimentshouldbelimitedtoasmallrangeofdesign.Inotherwords,experimentsshouldnotattempttooptimizeallstepsoftheproductorprocess.

2.Theestablishmentandstabilityofthegroup.Aprojectteamshouldbeselectedforexperimentationandanalysis.Theteamshouldbecomposedofpeoplewithproductandprocessknowledge,andsolicittheopinionsofallpersonnelrelatedtotheoptimizationdesign.Theydonotneedtohavein-depthtechnicalunderstandingofthesubjectrelatedtotheproblem,buttheteammembersshouldhaveexperienceinsimilardesigns.Theteamshouldbeabletoobtainknowledgeofstatisticalmethodsandspecialrobustdesigntechniquesthroughstatisticiansorpersonnelwhohavereceivedrobustdesigntraining.

3.Parameterselection.Therobustdesignmethoddoesnotincludescreeningexperimentstonarrowtheselectedparametersetoftheoptimaldesign.However,teammembersmayregardthisprogramasanopportunitytotestmoreparametersordifferentlevelsandcombinationsofthesameparameters.Inthiscase,ascreeningexperimentmayberequiredtonarrowdowntheselectionofparameters.

Приложение за устойчивост

Inpractice,robustnessiswidelyused.Duetotheinaccuracyofmeasurementandtheinfluenceofenvironmentalfactorsduringoperation,itwillinevitablycausethesystemCharacteristicsorparametersdriftslowlyandirregularly,sorobustnessmustbeconsideredwhendesigningvarioustypesofcontrolsystemsusingcomplexityparadigms.Suchasorganizationalbehaviormanagement,formulationofstrategicplanning,provisionofdecision-makingplans,restorationofecosystems,dynamicbalance,geneticnetworks,dampingofgeneticvariation,developmentofbiologicalcomplexity,automaticselectionofdirectedevolutionaryevolution,anddistributedfeedbackintheimmunesystem.Nervoussystem,computernetworksystem,economicgameofeconomicandsocialsystem,socialsystem,politicalagreement,institutionalmechanism,etc.

Itisworthmentioningthatwiththeprocessoffinancialliberalizationandglobalization,thetrendoffinancialinnovationhasgraduallystrengthened,theuncertaintyofthefinancialsystemhasincreasedsignificantly,thefinancialdecision-makingenvironmenthasbecomemorecomplex,thefinancialmarketenvironmentandfinancialFundamentalchangeshavetakenplaceintheoperatingcharacteristicsofinstitutions.Manyscholarshaveacceleratedtheirresearchontherobustnessofthefinancialsystem,usingtheirresearchresultsintheeffectivenessofinvestmentdecision-making,financialriskmanagement,assetallocation,etc.,andachievedsignificantresults.

Themosttypicalapplicationisincomplexadaptivesystems.However,itwillhavepracticalsignificanceonlywhenitcanbeusedinsomeenvironmentstoachieveeffectsthatcannotbeachievedinotherways.Atthesametime,wemustpayattentiontotheissuesofcostandbenefit.Asauniversallaw,therearestrictconservationlawsinrobustsystemsthatrequirehightoleranceforcertainscenariosandnecessarilylowtoleranceforotherscenarios.Forexample,anaircraftiseitherhighlymaneuverable,orverycapableofresistinganti-aircraftgunfire,butnotboth.Anotherexampleisthatthereisagameproblembetweeneconomicgrowthandenvironmentalprotection,andtheeconomymustdevelopfasterandinanorderlymanner.Toconsumeresourcesandhaveacertainimpactontheenvironment,andemphasizingenvironmentalprotection,tosomeextent,willrestricteconomicgrowth.Whendesigningandusingrobustnesstosolvetheaboveproblems,itisnecessarytoconsidercostandbenefitissues.

Related Articles
TOP