立体车库的英文文献中英文一起文档格式.docx

立体车库的英文文献中英文一起文档格式.docx

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1．Introduction

Inavarietyofproductmanufacturingindustries,themostautomatedformofproductionisaFlexiblemanufacturingsystem（FMS）,firstintroducedin1970s.SincetheFMSscanprovideahighpotentialforproductivityimprovementinbatchmanufacturing,thenumberofFMSsisgrowingsubstantially（GrooverandZimmers,1984）.Theaccelerationthroughouttheworldisduetoincreasedglobalcompetition,reducedmanufacturingcycletimes,andcutsinproductioncosts.

Generally,anFMSconsistsofagroupofmachinesorotherautomatedworkstations,whichformintomodularsubsystems,suchasCNCmachines,robots,visionsystems,andaprocessstation.Theseareinterconnectedbyamaterialshandlingsystemandusuallydrivenbyacomputer（Maleki,1991）.Eachmodularsystemrequiresanindividualmodularcontrolsystem,withdifferentcomponentsbeingcontrolledbyindividualcontrollerunits.Allofthemodularsubsystemsarecontrolledbycomputersasusual.Thesecontrollersperformtheirintendedtasksundersupervisionofahigherlevelcontroller.Tothesystem,boththecontroldevicesaswellastheflowofinformationneedtobeautomated.ThekeyaspectofanFMSisitsabilitytoadapttochangesinthecontroltasks.Thisflexibilityincludesthequantitiesandvarietiesofparttypeswhichitcanproduce,theorderinwhichoperationsmaybeperformed,anditsabilitytoreroutepartsbackintoflowpaths.Intheend,thecontrolplatformshouldhavethecapabilitytoautomatetheflowofinformation.

Typically,therearethreetypesofcontrolplatformsusedinFMSs:

minicomputers,microcomputers,andPLCs（Maleki,1991）.Theminicomputersarebestsuitedforcomplexlarge-scale,continuous,regulatorycontrolapplications.ThePLCsareusedforrapidandrepetitiouslogiccontrol.Personalcomputers（PCs）aresuitedforoperatorinterfacefunctions.Primarily,PLCsaredesignedtoreplacehardwiringrelays,tooperateinanindustrialenvironment,tobeeasilymodifiedbyplantengineersandmaintenancepersonnel,andtobemaintainedbyplantelectricians.Currently,withtheconvergenceofunderlyingmicroprocessortechnologyandsoftwareprogramming,manyusersfindthatPLCsprovideacost-effectivesolutiontoreal-timecontrolinsmall-tomedium-sizedprocessplants,especiallywhencombinedwithsupervisoryPCsusinghybridsystems.

Thepurposeofthisarticleistoaddressthestate-of-the-arttechnologyofFMSs.ThedesignandconstructionofanFMSusingPLC-controlledandPC-basedvisualman-machineinterface（MMI）anddataacquisitionsystem（DAS）arepresented.Itisorganizedasfollows.Section2beginswiththedescriptionoftheFMSonthefactoryflooroftheCenterforManufacturingSystemsattheNewJerseyInstituteofTechnology（NJIT）.Section3showstheoperationaldescriptionoftheFMS.Sections4and5presenttheapplicationsofPLC-controlledandPC-basedMMI/DASfortheFMSatNJIT.Section6containsasummaryoftheadvantagesofthisPLC-controlledandPC-basedMMI/DASforFMSapplication.

2.DescriptionoftheFMS

SIhandlingconveyorsystem

Thisconsistsoffourcarts,A,B,C,andD,withfixturesmountedoneach,twotransfertables,TT1andTT2,anddualconveyorswhichtransportmaterialstoeachworkstation.

Figure1.Flexiblemanufacturingsystem.

NASAIICNCmillingmachine

Themillingmachineacceptsrectangularsolidblanksandmachineseachpartofdifferenttypesaccordingtoitscomputercontroller.

GEP50robot

AsharedrobotisusedtoloadandunloadthematerialbetweentheCNCmillingmachineandtheconveyorsystem,andbetweenthepartspresentationstationandconveyorsystem.ItcontainsfivecomputerprogramsassignablebythePLC.ThecomputerprogramsdirecttherobottoloadthematerialbetweenthepartspresentationstationandthecartsandbetweentheCNCmachineandthecarts.Thelasttwoprogramsplacethecompletedpartsintheacceptorrejectarea.

Partspresentationstation

Thisstationincludesagravity-chute,whichsuppliesrectangularsolidblanksasrawmaterials.Thisstationalsocontainstwobintypes,oneeachforacceptedpartsandrejectedparts.

Computervisionsystem

Thevisionsystemprovidesforthevisualautomatedinspectionoftheparts.Itisamenu-driven,64-levelgrayscale,edgedetectionsystem.

Drillingmachine

AnIBM7535industrialrobotwithanautomateddrillasanend-effectordrillsvariousholesinthepartsasdirected.

Insummary,theFMShastworobots,oneCNCmill,amaterialtransferconveyorsystemincludingtransportationcartsandpositioninglimitswitches,andavisionsystem,whicharesupervisedbyaGE-SeriesSixPLCandmonitoredbyaPC-basedvisualMMI/DAS.

3.Operationaldescription

TheworkingcycleforthisFMSproceedsinthefollowingmanner:

1.Initially,allfourcartsontheconveyorsystemareemptyandavailablefortherawmaterialstobeloadedontothemfromthepartspresentationstation.

2.TheGErobotloadsfourparts,onebyone,ontothefourcartsontheconveyorsystem.Thecartsmoveclockwiseastheyarebeingloaded.

3.Figure2showsthepositionsacquiredbythefourcartsoncethefourpartsofdifferenttypeshavebeenloaded.

4.TheIBMrobotdrillsvariousholesoneachblankpartasthecartstopsatthedrillingmachine.

5.TheGErobotmovestotheconveyor,removesthepartfromthecartatpositionX1,andloadsitintothefixturelocatedontheCNCmachinetable.

6.OncethepartisloadedontheCNCmillingmachine,therobotretracts,andthemillingmachinemillstherectangularpartasrequired.

7.Afterthemillingoperation,therobotarmmovestothemillingmachinetoremovethepartthatwasmachinedfromtheholdingfixture.

Figure2.Loadingstateoftheconveyorsystem.

8.Therobotreturnsthefinishedparttothesamecartontheconveyor.

9.Asignalissenttothevisioncameratoinspectthepart.

10.Thevisionsystemanalyzesthepartandoutputsasignalthatdirectstherobottoacceptorrejectthepart.

11.Therobotrunseitheranacceptprogramtoplacethepartintheacceptbinorrunsarejectprogramtoplacethepartintherejectbin.

12.TheGErobotgoestothepartspresentationstationandloadsanewblankpartintothecart.

13.Thecartisreleasedtothesystemandthenextcycleisstarted.

4.ControlofanFMSwithaPLC

ThesignificantfeaturesoftheFMScontrolsystemareasfollows:

1.Thesystemiseasytoconfigureandtomodifytoaccommodatechangesandupdates,becauseoftheladderlogiccapabilityofthesystem.

2.Inasimilarmanner,thesystemiseasytoprogramanddocument.

3.Thesystemcanbeeasilymaintained,andtroubleshootingisdecreasedbecauseon-linediagnosticsareprovidedtopinpointproblemsanddecreasemaintenance.

4.Naturally,thesystemisreadilyinterfacedwiththecomputer.

ThePLCisageneralpurposeindustrialcomputerwhichiswidelyusedinindustrialprocesscontrol.Itiscapableofstoringinstructionstoimplementcontrolfunctionssuchassequencing,timing,counting,arithmetic,datamanipulation,andcommunicationtocontrolindustrialmachinesandprocesses.ThePLCischosentoperformanFMScontroltaskbasedonthefollowingfeatures:

1）goodreliability;

2）lessspacerequiredandoperatesinanindustrialenvironment;

3）easiertomaintainbyplantengineerortechnician;

4）canbereprogrammedifcontrolrequirementschange;

5）cancommunicateandnetworkwithothercomputers.

Inthisapplication,aGE-SeriesSixPLCisequippedwithamemorybank,andtheI/Oracksareloadedwiththefollowinginputandoutputinterfaces:

120VACinputmoduleswith8ports/module,24VDCinputmoduleswith8ports/module,and120VACoutputmoduleswith8ports/module.

5.PC-basedvisualoperatorinterfaceunit

Withtheconvergenceofmicroprocessortechnologyandsoftwaretechniques,thePChasbecomeveryusefulinoperatorinterfaceapplications.PCsrunningMMI/DASfront-endsmakepowerful,intuitiveoperationinterfaces,fullofusefulgraphicsandreportingtools.InformationfromthesePCscanbedistributedthroughacompany’slocalareanetwork（LAN）orwebusingclient-servertechnologies.

APC-basedvisualMMI/DASwasdevelopedtomonitortheprocessandlogdata.ThefunctionsoftheMMIaretwofold.First,ito