徐州工程學院畢業(yè)設(shè)計(外文翻譯)1徐州工程學院畢業(yè)設(shè)計外文翻譯學生姓名學院名稱機電工程學院專業(yè)名稱機械設(shè)計制造及其自動化指導教師2011年5月27日徐州工程學院畢業(yè)設(shè)計(外文翻譯)2Anexperimentalstudyontheoptimizationofcontrollergainsforanelectro-hydraulicservosystemusingevolutionstrategiesMinYoungKim,Chung-OhLeeDepartmentofMechanicalEngineering,KoreaAdvancedInstituteofScienceandTechnologyAbstractThispaperdealswithanexperimentaloptimizationproblemofthecontrollergainsforanelectro-hydraulicpositioncontrolsystemthroughevolutionstrategies(ESs)-basedmethod.Theoptimalcontrollergainsforthecontrolsystemareobtainedbymaximizingtnessfunctiondesignedspeciallytoevaluatethesystemperformance.Inthispaper,foranelectro-hydraulicpositioncontrolsystemwhichwouldrepresentahydraulicmillstandfortheroll-gapcontrolinplatehot-rollings,thetimedelaycontroller(TDC)isdesigned,andthreecontrolparametersofthiscontrolleraredirectlyoptimizedthroughaseriesofexperimentsusingthismethod.Itisshownthatthenear-optimalvalueofthecontrollergainsisobtainedinabout5thgeneration,whichcorrespondstoapproximately150experiments.Theoptimalcontrollergainsareexperimentallyconrmedbyinspectingthetnessfunctiontopologiesthatrepresentsystemperformanceinthegainspaces.ItisfoundthattherearesomelocaloptimumsonatnessfunctiontopologysothattheoptimizationofthethreecontrolparametersofaTDCbymanualtuningcouldbeataskofgreatdifculty.TheoptimizedresultsviatheEScoincidewiththemaximumpeakpointinopologies.Itisalsoshownthattheproposedmethodisanefcientschemegivingeconomyoftimeandlaborinoptimizingthecontrollergainsofuidpowersystemsexperimentally.Keywords:Controllergainoptimization；Evolutionstrategies；Timedelaycontrol；Automaticcontrollergainsearch；Electro-hydraulicservosystem1.IntroductionRecently,theresearchontheoptimizationandadaptationofcontrollergainsorparametersforimprovingthesystemperformanceinhydraulicandpneumaticservosystemshasbeenaeldofincreasinginterest(Fleming&Purshouse,2002；Klein,1992；Jeon,Lee,&Hong,1998；Hyun&Lee,1998；Choi,Lee,&Cho,2000).Ingeneral,whencontrolengineersdesigncontrollerforhydraulicorpneumaticservosystems,itisverydifculttodeterminetheoreticallyitscontrolgainstoexhibitthebestperformanceofthesystems,becausetheaccuratemodelingforthesesystemsishardduetohighlynonlinearcharacteristicsoftheuidpowersystems.Tobemore徐州工程學院畢業(yè)設(shè)計(外文翻譯)3specic,thehydraulicandpneumaticservosystemsalreadyhavearelativelyhigherdegreeofnonlinearitythanothermechatronicsystemslikeDCorACservosystems.Itresultsfromvariousfactors(Merrit,1976；Watton,1989):thepressure-owcharacteristicsofvalve,thesaturationofvalveandcylinder,theleakageowcharacteristicsofvalveandcylinderwithvariationofsupplypressure,thefrictioncharacteristicincylinder,thevariationofviscosityandcompressibilityofworkinguidwiththetemperature,theowcharacteristicduetotheshapeofpipeline,andmostimportantly,thevariationofthesystemgainswiththesupplypressureandtheloadpressure.Therefore,whentheseuidpowersystemsarecontrolled,thecontrollergainsareadjustedonthefoundationofexpertsintuitiveknowledgeaboutthesystemandthetuningexperienceofthecontrollergainsingeneral.Itneedsveryexcessiveexperimentsthroughtrialanderror.Butthoughsomecontrollergainsareobtained,itishardtosaythattheresultsarethebestgainsetatagivensituation.Fortheautomaticadjustmentofthecontrollergainsinuidpowersystems,theresearchtoapplicationofafuzzygainadapter(FGA)hasbeenperformed(Jeon,1997；Klein,1992).Inthiscase,theknowledgebaseisneededfortransplantationoftheexpertknowledgetothesystems,andsomegeneralrulestovariationofthesystemresponseduetovariationofthecontrollergainsaredemandedfortheconstructionofthisknowledgebase.Therefore,muchexpertsexperiencesandmanyexperimentsarenecessaryfortheimplementationofthisalgorithm.Inthisstudy,evolutionstrategies(ESs)isproposedasamethodoftheautomaticoptimizationofthecontrollergainsinaelectro-hydraulicsystem.ESisoneoftheevolutionaryalgorithmsbasedonthenaturalgeneticsandthesurvivalofthettest(Rechenberg,1973；Schwefel,1981；Back&Schwefel,1994,1996).Whenanappropriatetnessfunctionrepresentingpotentialsolutionsisgivenassurvivabilityofcandidates,thetuningproblemofcontrollergainscanbeconsideredasanoptimizationproblem,sothatanoptimalcontrollergainsetissearchedintheregionofgainspacesspeciedbyoperator.Amajoradvantageisthatmuchexperienceonthegain-tuningforthecontrolsystemisnotrequired,andtheleastinformationforthesystemisjustrequired.Especially,incasesthatarealexperimentalsystemisdirectlyusedforevaluatingcandidates,ESsaremoresuitablethanotherevolutionalgorithmsduetoitsowncharacteristiccalledself-adaptation.Inthisstudy,atimedelaycontroller(TDC)isdesignedasacontrollerforpositioncontrolofanelectro-hydraulicservosystem.Thecontrollerdesignedtohave2ndordererrordynamicshasthreecontrollergainsimplicitly.ByusinganESasoptimizationalgorithms,theoptimalcontrollergainsetinthespeciedgainspacesisdeterminedthroughonlineexperiments.Forthevericationoftheobtainedresults,thetnessfunctiontopologiesinthegainspacesexperimentallyaremadeout,andanalyzed.Finally,theexperimentalresultssearchedthrough徐州工程學院畢業(yè)設(shè)計(外文翻譯)4ESsareshowntocoincidewiththeoptimalpeakpointthathasbesttnessvalueonthespeciedgainspaces.2.Hydraulicservosystem2.1.Electro-hydraulicpositioncontrolsystemFig.1istheschematicdiagramoftheelectro-hydraulicpositioncontrolsystemusedinthisstudy.Thissystemisatestrigfortheroll-gapcontrolofhydraulicmillstand,whichwasmadefortheimprovementofthicknesscontrolperformanceinplatehot-rollingprocesses(Gizburg,1984；Lee,Lim,&Park,1997).Therigsimulatesaroll-gapcontrolsystemcomposedofahydraulicmillstandinanumberofautomaticgaugecontrolsystemsforhotrollingprocesses.Thesystemconsistsofstructurespringtorepresentamodulusofmillstand,materialspringtorepresentamodulusofrolledstrip,roll-gapcontrolcylindertocontroladeformationofmaterialspring,anddisturbancecylindertogivethecontrolsystemadisturbance.Theforceappliedtoroll-gapcylinderismeasu