Vehicle System Dynamics Understanding and Modellin

VehicleSystemDynamics0042-3114/03/4001–3-101$16.002003,Vol.40,Nos.1–3,pp.101–134#Swets&ZeitlingerUnderstandingandModelingtheHumanDriverCHARLESC.MACADAM1SUMMARYThispaperexaminestheroleofthehumandriverastheprimarycontrolelementwithinthetraditionaldriver-vehiclesystem.Lateralandlongitudinalcontroltaskssuchaspath-following,obstacleavoidance,andheadwaycontrolareexamplesofsteeringandbrakingactivitiesperformedbythehumandriver.Physicallimitationsaswellasvariousattributesthatmakethehumandriveruniqueandhelptocharacterizehumancontrolbehavioraredescribed.Exampledrivermodelscontainingsuchtraitsandthatarecommonlyusedtopredicttheperformanceofthecombineddriver-vehiclesysteminlateralandlongitudinalcontroltasksareidentified.1.INTRODUCTIONItshouldfirstbenotedthatthegeneraltopicsof(1)understandinghumandriversand(2)modelingtheirbehavior,arequitebroadinscope,eithertakenaloneortogether.Inordertoboundthispapertoasomewhatmoremanageablescale,theemphasishereisonthecontrolaspectofthehumandriveranditssubsequentconceptualorcomputer-basedmodeling.Thatistosay,manybehavioralaspectsofdriving–lessrelatedtocommoncontroltaskactivitiessuchaspath-following,obstacleavoidance,orheadwaycontrol–arenotbeingaddressed.Suchbehavioralactivitiesmightincludeitemslikedriverdistraction,side-tasking,ordriverimpairmentsthataremoreintherealmofhumanfactorsinterests.Rather,thefocushereisonthesteeringorbraking/accelerationcontrolbehaviorofhumandriverscommonlyobservedtobepresentforbothlateralandlongitudinalcontrolofthevehicle.Theprincipalrootsofdrivermodelingasitrelatestothesecontrolactivitiesextendbacktotheearlyyearsofhuman-machineandaircraftpilotstudies[1–14].Thosestudieshelpedtorevealvariouspropertiesuniqueto,orcharacteristicof,thehumanasacontrollerofdynamicalplants[1,4,8,14,15]andcertainvehicles[6,16–20].Forexample,in1961Ornstein[8]proposedthefollowingtransferfunction,H(s),modelofthehumanoperatorforpursuit-typemanualtrackingtasks,HðsÞ¼ða1$sþa0Þ$e&s!=ðb2$s2þb1$sþb0Þð1Þ1Addresscorrespondenceto:C.C.MacAdam,TheUniversityofMichigan,TransportationResearchInstitute,2901BaxterRoad,AnnArbor,MI48109USA.Tel.:[phone];E-mail:[e-mail]:[UniversityofMichigan]At:21:3422February2010andnotedthatthenumeratorcoefficienta1associatedwiththevelocitycomponent,oranticipatorybehaviorofthehumanoperator,wasadaptivetochangingplantdynamicsandmethodsofvisualpresentation.Ineffect,thiswasanearlyobservationoftheadaptivenatureofahumanwheninteractingwithdifferentorchangingplantdynamicsandtheuseofpredictionbythehumanoperator.Theparametertwasaneffectivetransporttimedelay.Morespecificstudiesaimedatunderstandingthehumanasanautomobiledriver[16,19–31]followedfromorparalleledthistypeofmanualcontrolwork.OneexampleisaseriesofpublicationsbyRashevskyinthelate1950sandearly1960sthataddressedthetopicof‘‘MathematicalBiologyofAutomobileDriving’’[25]whereinthebasicmodelofthedriverasasteeringcontrollerwastreatedinapurelygeometric/kinematicmanner.Theproposedalgorithmforsteeringanautomobileofdesignatedwidthandlengthalongastraightroadofspecifiedwidthamountedtoissuinginstantaneoussteeringcorrectionstothevehiclewheneveritapproachedtowithinaspecifiedmarginofeitherlaneedge.Althoughnovehicledynamicswereconsideredwithinthismathematicaltreatment,driveranticipationanddriverdelaypropertieswereincludedaskeyparameters.Rashevskyinterestinglyobservesinonework[32],Tosumup,weseethatthecombinationofhumanparametersandofmechanicalparametersenterintotheprocessofdrivinginamannerwhichdoesnotpermittheirclear-cutseparation.Thecarandthedriverform,inasense,anindividuum.Andinanotherwork[33],Thecaranddriverconstituteacomplexfeedbacksystem.Thebehaviorofthecarresultsincertainreactionsbythedriver.Inversely,thebehaviorofthedriveraffectsthebehaviorofthecar.This‘man-machine’systemcannot,inmanyinstances,beseparatedintothepurely‘mechanical’andthepurely‘human’components.Thesystemmustbetreatedasawhole.Soweseethattheideaoftreatingthedriverandvehicletogetherasacombinedsystemwasrecognizedasimportantbyresearchers,absentevendynamicalconsiderationsofthevehicleresponse.Morecompletetreatmentsofthedrivermodelingeffortandassociatedmeasurementsofdriver-vehiclesystemresponseswerealsoemerginginthissametimeframe,particularlywiththeincreaseduseofcomputersanddrivingsimulators.ExampleworksthatstudieddrivercontrolbehaviorandaccountedforthedynamicsofthevehicleincludestudiesbyWierwille[19],McRuer[22],Weir[18,29–31],Kondo[17],Yoshimoto[20]aswellasmanyothers[16,26–28,34–37].Keyfindingsfromthesestudiesandothersthatfollowedarediscussedfurtherinsubsequentsectionsofthepaper.OthersurveypapersrelatedtothetopicofdrivercontrolbehaviorandmodelingarefoundaswellinsuchworksasGood[38],Reid[39],Guo[40],andPeng[41].102C.C.MACADAMDownloadedBy:[UniversityofMichigan]At:21:3422February2010Inmanycases,motivationforunderstandingandmodelingthedrivermaybeprimarilyrelatedtoachievingimprovementsinvehicledesignperse,insofarasaninteractive,orcauseandeffect,relationshipisrecognizedbetweenthevehicleandthedriver[28,38,42–51].2.CHARACTERISTICSOFTHEHUMANDRIVERThissectionofthepaperdescrib