液压挖掘机.docx

液压挖掘机.docx

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液压挖掘机

JournalofZhejiangUniversity-SCIENCEA（AppliedPhysics&Engineering）ISSN1673-565X（Print）;ISSN1862-1775（Online）

E-mail:

jzus@

Quantitativemeasuresforassessmentofthehydraulicexcavatordiggingefficiency*

DragoslavJANOSEVIC†1,RosenMITREV2,BobanANDJELKOVIC1,PlamenPETROV2

（1FacultyofMechanicalEngineering,UniversityofNis,Nis18000,Serbia）（2FacultyofMechanicalEngineering,TechnicalUniversityofSofia,Sofia,Bulgaria）

†E-mail:

janos@masfak.ni.ac.rs

ReceivedNov.18,2011;RevisionacceptedMar.27,2012;CrosscheckedNov.1,2012

Abstract:

Inthispaper,quantitativemeasuresfortheassessmentofthehydraulicexcavatordiggingefficiencyareproposedanddeveloped.Thefollowingfactorsareconsidered:

（a）boundarydiggingforcesallowedforbythestabilityofanexcavator,（b）boundarydiggingforcesenabledbythedrivingmechanismsoftheexcavator,（c）factorstakingintoconsiderationthediggingpositionintheworkingrangeofanexcavator,and（d）signanddirectionofpotentialdiggingresistiveforce.Acorrecteddiggingforceisdefinedandamathematicalmodelofkinematicchainanddrivemechanismsofafive-memberexcavatorconfigurationwasdevelopedcomprising:

anundercarriage,arotationalplatformandanattachmentwithboom,stick,andbucket.Onthebasisofthemathematicalmodeloftheexcavator,softwarewasdevelopedforcomputationanddetailedanalysisofthediggingforcesintheentireworkspaceoftheexcavator.Byusingthedevelopedsoftware,theanalysisofboundarydiggingforcesisconductedandthecorrecteddiggingforceisdeterminedfortwomodelsofhydraulicexcavatorsofthesamemass（around17000kg）withidenticalkinematicchainparametersbutwithdifferentparametersofmanipulatordrivingmechanisms.Theresultsoftheanaly-sisshowthattheproposedsetofquantitativemeasurescanbeusedforassessmentofthediggingefficiencyofexistingexcava-tormodelsandtoserveasanoptimizationcriterioninthesynthesisofmanipulatordrivingmechanismsofnewexcavatormodels.

Keywords:

Hydraulicexcavators,Diggingefficiency,Quantitativemeasures

doi:

10.1631/jzus.A1100318Documentcode:

ACLCnumber:

TV53

1Introduction

Thehydraulicexcavatorsarepopularmultifunc-tionalconstructionandminingmachines.Themainfunctionofthehydraulicexcavatorsofalltypesandsizesisthecyclicdiggingandtransferofsoil.ThisfunctionisachievedbyuseofanopenkinematicchainconsistingofundercarriageL1,anupperstruc-tureL2andafrontattachmentwithboomL3,stickL4andworktoolL5（Fig.1）.Fordiggingoperationsbelowthegroundlevel,thetowardoneselftechnol-ogy（inrelationtotheexcavatoroperator）isem-ployedandabackhoeattachmentisused（Fig.1a）.

*Project（No.035049）partlysupportedbytheMinistryofEducationandScienceoftheRepublicofSerbia

©ZhejiangUniversityandSpringer-VerlagBerlinHeidelberg2012

Fordiggingoperationsabovethegroundleveltheawayfromoneselftechnologyandashovelattach-mentareused（Fig.1b）.

Duringdiggingoperations,theoccurringdig-gingresistiveforceactingagainstthemanipulatortoolisovercomebydiggingforces.Thediggingforcesofanexcavatorareexertedbythekinematicchainoftheexcavator,whichispoweredbythefol-lowingdrivingmechanisms:

（1）hydraulicmotorsformotionofswingandtravellingbodies;

（2）doubleactinghydrauliccylindersforpoweringofthema-nipulatorlinks.

Foranoptimaldesignofthefrontmanipulatoranddrivingmechanisms,itisnecessarytoperformadetailedanalysisofthediggingforcesandthediggingresistiveforcesintheentireworkspaceoftheexcava-tor.Theconductedanalyticalandexperimental

researchthatpointsouttheimportanceofknowledgeaboutthediggingresistiveforcesfordevelopmentandanalysisofhydraulicexcavatorsisrelatedto:

（1）analyticalmodelingandexperimentaldeterminationofthevalueandthechangeinthediggingresistiveforceduringtheexcavationprocess（MaciejewskiandJarzebowski,2002;Maciejewskietal.,2003;Yangetal.,2008）;

（2）developmentofmathematicalmodelsforkinematicanddynamicanalysisofexca-vators（Budnyetal.,2003;Towarek,2003;HallandMcAree,2005;Guetal.,2007）;（3）developmentofcontrolsystemsforautomationofthediggingproc-ess（Ploneckietal.,1998;Haetal.,2000;ChangandLee,2002;LeeandChang,2002;Floresetal.,2007;Linetal.,2008）;and,（4）definitionofquantitativemeasuresforanalysisandassessmentofexcavatordiggingefficiencyintheworkspace.

L

L3

2

L4

L5

L1

（a）

L3

L2

L4

L5

L1

（b）

Fig.1Hydraulicexcavatorswithbackhoe（a）andshovelattachment（b）

Asindicatedbythemanufacturer,stickandbucketdiggingforcesareimportantparametersoftheexcavator.Theyaredefinedbyappropriatestan-dards（ISO6015,2006;SAEJ1179,2008）asoneofthecharacteristicsoftheexcavatordiggingfunction.Forroboticmanipulators,quantitativemeasuresofworkspaceattributesaredefined,whichincludesstructurallengthindexandmanipulabilitymeasure

（Craig,2005）.Someofthesemeasurescanbeusedfortheassessmentofthedynamicperformanceofshovels（Lipsett,2009）.Inmanycases,theabovementionedmeasuresarenotsufficientforassessmentofdiggingpossibilitiesandefficiencyoftheexcava-torintheworkspace.

Inthispaper,asetofquantitativemeasuresforassessmentofthehydraulicexcavatordiggingeffi-ciencyisproposedanddeveloped.

Foracomprehensiveanalysisofvaluesanddi-rectionsofdiggingforcesinaspecificpositionofthefrontmanipulator,ahodographofboundarydiggingforcesatthetopofthebuckettoothisdefined.Ithasaformofapolygonwhosesidesarecomposedbyvectorsofboundaryforcesexertedbythemanipula-tordrivingmechanismsandvectorsofboundaryforcesallowedbythestabilityoftheexcavator.Theratioofthecomputeddiggingforceandthepotentialdiggingforceisdefinedasameasureofthediggingefficiency.Thecomputeddiggingforceisdeter-minedbyamathematicalmodeloftheexcavator.Computationsareperformedforagivenpositionandorientationofthemanipulatorandpressuresinthehydrauliccylindersofdrivingmechanisms.Thepo-tentialdiggingforcerepresentstheminimumvalueofboundarydiggingforces（Dudczak,1977）.

Ahodographoftheeffectivediggingforcesisdefinedasapartofthehodographoftheboundarydiggingforces,forwhichthedotproductofthedig-gingvelocityanddiggingforcevectorispositive.Theratiooftheareaandrangeoftheeffectivedig-gingforceshodographisacceptedasacriterionforexcavatordiggingefficiency,whereastheareaoftheeffectivehodographrepresentsthemeanvalueofthealloweddiggingforces.Therangeofthehodographoftheeffectivediggingforcesreflectsthedegreeofcompatibilityofmanipulatoractuatorparameters,excavatorweightdistribution,anddiggingforcedis-tribution（Budny,1989）.

Acorrecteddiggingforceissetasameasureofdiggingefficiencyintheentireworkspace.Thefol-lowingconsiderationsaretakenintoaccount:

bound-arydiggingforcesallowedbythestabilityofanex-cavator;boundaryforcesexertedbythedrivingmechanismsofanexcavator;andfactorswhichre-latetothediggingpositionofthemanipulatorintheworkspaceaswellasthesignanddirectionofthepotentialdiggingresistanceaction（Janosevic,1997）.

Inthispaper,mathematicalmodelsoftheexca-vatorkinematicchain,drivingmechanismsandboundarydiggingforcesareproposedanddeveloped.

2Mathematicalmodelingofexcavator

AsideviewoftheexcavatorisshowninFig.2.Themathematicalmodeloftheexcavatorconsistsofthemathematicalmodeloftheexcavatorkine-maticchainandthatofthemanipulatordrivingmechanisms.

2.1Modeloftheexcavatorkinematicchain

Theexcavatorrepresentsafive-linkopenkine-maticchainwhichconsistsofthetravellingbodyL1,theswingbody（rotationalplatform）L2andthethree-linkfrontmanipulatorconsistingofaboomL3,astickL4,andabucketL5（Fig.2）.

Thelinksofthefrontattachmentkinematicchainareconnectedbykinematicpairsofthefifthclass–rotationaljointswitha1DOFwithdifferentorientationsinthespace.Thekinematicchainofthefrontmanipulatorwhichisapartoftheexcavatormodelisplanar.ThecentersofthemanipulatorjointsOi（i=3,4,5）arepenetrationpointsofjointaxisthroughtheplaneofsymmetryofmanipulatorchain

torisconsideredasanopenkinematicchainwithalastlink（bucket）thatissubjectedtothediggingre-sistiveforceW（Janosevic,1997）.

Todescribemathematicallythekinematicmodeloftheexcavator,thefollowingcoordinatesystemshavebeenassigned:

（1）GlobalreferenceframeOXYZwithunitvectorsi,j,kalongthecoordinateaxesOX,OY,andOZ,respectively.Thesupportbaseliesinthehori-zontalplaneOXZandtheverticalaxisOYcoincideswiththeaxisoftherotationaljointbetweentheun-dercarriageandupperstructureO2.

（2）BodyfixedcoordinatesystemsOixiyizi（i=1,

2,3,4,5）,whichareconnectedtoeachlinkLiofthekinematicchain.ThecoordinatesystemsbeginningOiissituatedinthecenterofjointbywhichthechainmemberLiisconnectedtothepreviousmemberLi−1.ThebucketisconnectedtoacoordinatesystemwhoseaxisO5x5passesthroughthecenterofthejointO5andthetopofthecuttingedgeofthebucketOw.

Inthecaseofthestationaryundercarriage,thecoordinatesystemO1x1y1z1coincideswiththeglobalcoordinatesystem.

ThegeometryofthekinematicchainlinksLiisdefinedinitslocalcoordinate