实时压力监测和控制的无传感器液压系统

P.Wenetal.(Eds.):RSKT2009,LNCS5589,pp.467–474,2009.©Springer-VerlagBerlinHeidelberg2009Real-TimePressureMonitoringandControlofaHydraulicSystemwithoutSensorTianshuPeng1,CraigStruthers2,andPengWen21ComputingCentreofGansuProvincialDepartmentofScience&TechnologyLanzhou,GansuProvince730030,[e-mail]2FacultyofEngineeringandSurveyingUniversityofSouthernQueenslandToowoomba,QLD4350,[e-mail]ystem,apressuresensorisusedtoimple-mentfeedbackcontrol.However,therearemanyindustrialcaseswhereapplica-tionshaverequiredapressurefeedbackbutthemediaissocorrosiveand/ordangerous,thesensorbecomesprohibitivelyexpensive.Thisresearchproposesthecontrolofapumpingsystemwhichcanachievethedesiredpressurewithoutapressuresensor.Alongwiththecontrolsystemitself,auserfriendlyinterfaceisdevelopedtooperateovertheEthernet.Keywords:systemreliability,ModbusProtocol,pressuretransducer,EthernetnetworkandWEBserverinterfaces.1IntroductionThereareagreaternumberofpumpswhichareutilizedinalmostallaspectsofindus-tryandengineering,andrangewidelyfromfeedstoreactors,distillationcolumnsinchemicalengineeringandpumpstormwaterincivilandenvironmentalengineering.Thereisanalmostendlessassortmentofpumpingequipmentavailableranginginsize,typeandmaterialofconstruction[6,8].Researchcontributingtoadvancementsinpumpingtechnologycanpotentiallycreateimmensebenefitsforalargeproportionoftheengineeringandindustrysectors.Currently,withintheindustrialfieldthereappearstobeadeficiencyinproductsdesignedspecificallyforthecontrolofpumpingsystems.Thisisparticularlyevidentintheapplicationofconstantpressureinahydraulicssystem.Thecurrentindustrystandardistoperformthisprocesswithmultipleunitsandapressuretransmitterfeed-back.Fig.1demonstrateshowpressurecontrolinahydraulicpumpingsystemiscurrentlyachieved.NoteinparticulartheuseofapressuretransmitterinconjunctionwithacontrollerandaVariableSpeedDrive.Theresearchwaschoseninordertofindapracticalsolutiontoachievingpressurefeedbackinpumpingapplicationswithhighlycorrosiveordangerousmediums.Atpresent,thisparticularaspectofthepumpingindustrydoesnotappeartobeade-quatelyaddressed.Althoughpressuretransmittersareavailableformediumsthatareconsidereddangerousandcorrosivethecostofthiscomponentishighlyprohibitive.468T.Peng,C.Struthers,andP.WenFig.1.IllustrationofexistingPressureControlSystemFurthermore,replacementorcalibrationofthepressuretransmittercomponentcanbedifficultandagainnotcosteffectiveundersuchsevereconditions.Researchintocurrentinitiativesrevealsthatthemaindevelopmentsinsensorlesspumpcontrolarebeingundertakenpredominantlywithinthemedicalfieldsuchasartificialheartsandbloodpumps.Theobjectivebeingtoremovetheinvasivepressuretransmittercomponentfromwithinthehumanbody[7,9].Thisresearchproposestodevelopapumpingcontrollerabletomaintainconstantpressurewithinthehydraulicssystemwithoututilizingapressuretransmitterandcontroller.Themainpurposeofthisundertakingistoensurethatthecontrollerwillhavenophysicalcontactwiththemedium.Thusremovingthepressuretransmittercomponentofpumppressurecontrolinordertoachievethereductionofacompo-nent.Incompletingthefunctionality,areal-timemonitoring,configurationandcon-trolsystemsoftwarepackageisalsobeingdeveloped.2MethodologyThisresearchproposestoremovethepressuretransducercomponentofpumppres-surecontrolinordertoachieveanefficientprocess[5].Fig.2representstheproposedpressurecontrolsystemwherebyallthepressurecontrolisperformedwithintheVariableSpeedDriveitself,theWEBserverissimplyaremoteuserinterface.Fig.2.IllustrationofproposedPressureControlSystem2.1SystemConfigurationTheculminationofsomespecifiedequipmentthatwillbelistedinnextsectionre-sultedinthefinaltestproductascanbeseenfromFig.3.Theoutletofthepumpfeedsintothetankcreatingaclosedloopsystem.ThepressuretransmitterhasthenbeenconnectedbackintotheVSDandtheVSDisthenmonitoredforpressure,speedandmotorcurrentreadings.Fig.4showsphoto’softheactualtestequipmentused.Real-TimePressureMonitoringandControlofaHydraulicSystemwithoutSensor469Fig.3.ClosedLoopTestingSystemPIDiagramFig.4.ThisPhotographisofClosedLoopTestingsystemandTestingSystem’sPump,Pres-sureTransmitterandVSD2.2SystemComponentsFollowingisthecomponentsthathavebeenutilizedforthisproject.Eachitemhasbeencarefullychosenforitssuitabilityforthepurposeoftheresearch.Apumpingsystemessentiallyconsistsasupplyorsuctionside,apumpwithadriverandadischargeordeliveryside[8].Acentrifugalpumpalternativelyisknownasapressuregeneratorbecauseitsrotatingelementtransferstheenergytothefluid[2,8].Notwithstandingthefactthatthecentrifugalpumpisoneofthemostwidelyusedpumpsfortransferringliquids,italsohasexcellentabilitytocontrolpressure,isquietincomparisontootherpumps,hasrelativelylowoperatingandmaintenancecosts,takesupminimalfloorspaceandcancreateauniform,nonpulsatingflow[2,3].Forthesereasonsabove,thetypeofpumpchosenisaCentrifugalpumpwithaRa-dialFlowImpellerdrivenbyasuitablysizedSquirrelcageinductionmotor.Thisformofpumpconsistsofashaftmountedimpellersrotatingunidirectionallywithinacasing.Thevelocityheadisconv