外文翻译--DSP控制电液伺服驱动.doc

翻译英文DSPControlofElectro-HydraulicServoActuatorsRichardPoleyDSPFieldApplicationsABSTRACTHydraulicactuatorsarecharacterizedbytheirabilitytoimpartlargeforcesathighspeedsandareusedinmanyindustrialmotionsystems.Inapplicationswheregooddynamicperformanceisimportantitiscommontocontaintheactuatorinaservoloopcomprisingafeedbacktransducerandelectroniccontroller.Themajorityofelectronicservo-controllersusedinthesesystemsareanaloguebasedimplementationsofthewell-knownPIDtype.However,therequirementtoimplementadvancedcontrolstrategieshasledtoanincreasedinterestintheuseofdigitalsignalprocessors(DSPs)inthisfield.Onedesignapproachwhichmeritsspecialconsiderationistheuseofcomputersimulationsoftwaretomodelthehydraulicplantandelectronicservo-controller,andtogenerateandtestembeddedcodeforthetargetDSP.Thisapplicationreportdiscussessomeoftheissuesinvolvedincontrollinglinearhydraulicactuators,andthesuitabilityoftheTMS320C28xDSPforsuchsystems.1IntroductionTherangeofapplicationsforelectro-hydraulicservosystemsisdiverse,andincludesmanufacturingsystems,materialstestmachines,activesuspensionsystems,miningmachinery,fatiguetesting,flightsimulation,papermachines,shipsandelectromagneticmarineengineering,injectionmouldingmachines,robotics,andsteelandaluminiummillequipment.Hydraulicsystemsarealsocommoninaircraft,wheretheirhighpower-to-weightratioandprecisecontrolmakesthemanidealchoiceforactuationofflightsurfaces.Althoughelectricalmotorsaresometimesusedinmanyoftheseapplications,motioncontrolsystemsrequiringeitherveryhighforceorwidebandwidthareoftenaddressedmoreefficientlywithelectro-hydraulicratherthanelectromagneticmeans.Ingeneral,applicationswithbandwidthsofgreaterthanabout20Hzorcontrolpowergreaterthanabout15kW,mayberegardedassuitableforservo-hydraulictechniques.Apartfromtheabilitytodeliverhigherforcesatfastspeeds,servo-hydraulicsystemsofferseveralotherbenefitsovertheirelectricalcounterparts.Forexample,hydraulicsystemsaremechanically“stiffer”,resultinginhighermachineframeresonantfrequenciesforagivenpowerlevel,higherloopgainandimproveddynamicperformance.Theyalsohavetheimportantbenefitofbeingself-cooledsincethedrivingfluideffectivelyactsasacoolingmediumcarryingheatawayfromtheactuatorandflowcontrolcomponents.Unfortunatelyhydraulicsystemsalsoexhibitseveralinherentnon-lineareffectswhichcancomplicatethecontrolproblem.Thevastmajorityofelectronicclosedloopcontrollersarebasedonsimpleanaloguecircuitdesignsofferingrobust,lowcostimplementationsofthewellknownPIDcontrolstrategy.Thisapproachworkswellinsystemswithsimpletopologyandlimitedbandwidth.Howeverthegrowinguseofcomplexcontrolstrategies,coupledwiththeneedtosupportenhancedfeaturessuchasdata-logginganddigitalcommunications,hasledtoincreasedinterestintheuseofdigitalprocessorsforcontrolofhydraulicservo-systems.Nowhereisthismoreapparentthaninthefieldofmechanicaltestequipment,wheretheuseofaprogrammabledigitalprocessorallowsthesameservocontrollertobeusedwithawiderangeofhydraulicsystems.Thisapplicationreportreviewssomeoftheissuesfacingthehydrauliccontrolengineeranddiscussesthesuitabilityofhigh-speedDSPsforcontrolofservo-hydraulicsystems.TheapplicationreportbeginswithanevaluationoftheDSPforuseinelectro-hydraulicservo-controllers,andintroducestheTMS320C28xfamily:aDSPplatformoptimizedfordigitalcontrolapplications.Section3describestheprincipalcomponentsofthehydraulicsystem.InSection4,mathematicalmodelsforthevariousplantelementsaredevelopedandusingSimulink.Section5presentsacasestudyofahydrauliccontrolsystemanddealswithfittingrealdatatothemodeltovalidateitsbehavior.Theapplicationreportconcludeswithabriefsummaryanddiscussionoftheapplicationanddesignprocess.2TheC2000DSPforDigitalControl2.1TheBenefitsofDSPforDigitalControlEmbeddeddigitalcontrollersofferseveralimportantbenefitstotheelectronicdesignengineer,including:sTheperformanceofahighqualityhydraulicactuatorisverydependantontheservo-controller.DSPslendthemselveswelltoimplementingreal-timecontrolalgorithms,andhavebeenwidelyusedinhigh-performancedigitalcontrollersformanyyears.Inadditiontothebenefitsabove,aDSPallowstheengineerto:dcontrolstrategies,includingmulti-variableandcomplexcontrolalgorithmsusingmodernintelligentmethodssuchasneuralnetworksandfuzzylogic.performadaptivecontrol,inwhichthealgorithmdynamicallyadaptsitselftomatchvariationsinsystembehavior.implementcomplextopologiessuchasmulti-axiscontrolwheresynchronizationofmultipleforcepatternsisrequired.performdiagnosticmonitoring,includingfrequencyspectrumanalysistoidentifymechanicalvibrationsandpredictfailuremodes.efficientlyimplementhigh-orderdigitalfiltersincludingsharpcut-offnotchfilterstoremoveenergythatwouldotherwiseexciteresonantmodesandpossiblyleadtoinstability.dperipheralsettominimizecomponentcountandboardsize.Theuseofdigitalcontrollersissometimesavoidedontheexpectationthattheuserisobligedtoinvesttimeinlearningnewprogramminglanguages,andwillfacedifficultiesintestingandde-buggingthecode.TheTexasInstrumentsC28xDSPplatformincludesahighperformanceCcompilerandanextensivesetofsoftwarelibrariestominimizedevelopmenteffort.Recentdevelopmentsinsimulationsoftwarealsoenabledesignerstomodelfixed-pointdigitalprocessors,andtoautomaticallygenerateoptimizedsourcecodewhichmaybecompiledandrunonthetargetprocessordirectlyfromthesimulationenvironment.This“hardware-in-the-loop”approachenablesthecontrolalgorithmsgeneratedbythemodeltobeexecutedonarealtargetprocessorsuchastheC28xduringsimulation,andincreasesthelevelofdesignconfidence.Theeasewithwhichcontrolalgorithmscanbecreatedandmodifiedinthismannercansavemonthsofdevelopmenttimeandleadstoearliererrordetectioncomparedwithtraditionalhandcodingmethods.2.2TheTMS320C28xDSPFamilyThechoiceofprocessortoimplementagivencontrol