OpenSim-Tutorial1-for-30-and-31

OpenSimTutorial#1IntroductiontoMusculoskeletalModelingScottDelp,AllisonArnold,SamuelHamnerNeuromuscularBiomechanicsLaboratoryStanfordUniversityI.OBJECTIVESIntroductiontoOpenSimModelsofthemusculoskeletalsystemenableonetostudyneuromuscularcoordination,analyzeathleticperformance,andestimatemusculoskeletalloads.OpenSimisopen-sourcesoftwarethatallowsuserstodevelop,analyze,andvisualizemodelsofthemusculoskeletalsystem,andtogeneratedynamicsimulationsofmovement[1].InOpenSim,amusculoskeletalmodelconsistsofrigidbodysegmentsconnectedbyjoints.Musclesspanthesejointsandgenerateforcesandmovement.Onceamusculoskeletalmodeliscreated,OpenSimenablesuserstostudytheeffectsofmusculoskeletalgeometry,jointkinematics,andmuscle-tendonpropertiesontheforcesandjointmomentsthatthemusclescanproduce.WithOpenSim,ourgoalistoprovideaframeworkthatallowsthebiomechanicscommunitytocreate,share,andextendalibraryofmodelsanddynamicsimulationtools.PurposeThepurposeofthistutorialistointroduceuserstoOpenSimbydemonstratingtheutilityofgraphics-basedmusculoskeletalmodelingandillustratinghowmuscle-tendonlengthsandmomentarmsdependuponlimbconfiguration.Inthistutorial,youwill:•BecomefamiliarwithOpenSim’sgraphicaluserinterface(GUI)•Discoversomelimitationsofmusculoskeletalmodels•Exploredifferencesbetween“1-joint”(uni-articular)and“2-joint”(bi-articular)muscles•UseOpenSimtoaddressanimportantclinicalproblemFormatEachsectionofthetutorialguidesyouthroughcertaintoolswithinOpenSim’sGUIandasksyoutoanswerafewquestions.ThemenutitlesandoptionnamesyoumustselectandanycommandsyoumusttypetorunOpenSimwillappearinboldface.ThequestionscanbeansweredbasedoninformationfromOpenSimandbasicknowledgeofthehumanmusculoskeletalsystem.Asyoucompleteeachsectionofthetutorial,feelfreetoexploreOpenSimandthelowerextremitymodelfurtheronyourown.Dependingontheamountofexplorationyoudo,thistutorialwilltakeabout1-2hourstocomplete.OpenSim:IntrotoMusculoskeletalModelingPage2IntroductiontotheOpenSimGUIThereareseveralkeycomponentsoftheOpenSimGUIthatwillbereferredtothroughoutthetutorial.ThetablebelowwillintroduceyoutotheseGUIcomponents.GUIComponentsTitleScreenshotToolbarMotionTextBoxMotionSlider/VideoControlsViewWindowNavigatorWindowCoordinatesWindowPropertiesWindowOpenSim:IntrotoMusculoskeletalModelingPage3II.MUSCULOSKELETALMODELOFTHELOWEREXTREMITYInthissection,youwillloadamodelofthelowerextremity[2]intoOpenSimandmakethemodel“walk.”Themodelrepresentsanadultsubjectwithanapproximateheightof1.8mandanapproximatemassof75kg.Themodelconsistsof13rigidbodysegmentsandincludesthelinesofactionof86muscles(43perleg).LoadingaModelThefirstmodelyouwillanalyzeisentitledBothLegswithMuscles.ToloadthismusculoskeletalmodelintoOpenSim:•ClicktheFilemenuandselectOpenModel.•FindtheModelsfolder,whichislocatedunderyourOpenSiminstallationdirectory,e.g.,C:\OpenSim3.0.Note:ThereareseveraldifferentexamplemodelsandmotionsintheModelsfolder.AllofthemodelandmotionfilesusedintheremainderofthetutorialwillbelocatedinthisModelsfolder.•OpentheBothLegsfolder,selectthefileBothLegs.osim,andclickOpen.Afterloadingamodel,itsnamewillappearintheNavigatorwindow.ToseetheNavigatorwindow,whichalsoprovidesspecificinformationaboutthebodies,muscles,andjointsinthemodel,clicktheWindowmenuandselectNavigator.ToexpandaNavigatorheading,clicktheplusicontoitsleft.Note:Ifalreadyopened,youcanalsoviewtheNavigatorwindowbyclickingitstitlebar.Viewing&AnimatingaModelOpenSimallowsyoutoorientthemodelusingyourmouse.ROTATETorotatetheview,clickandholdtheleftmousebuttonanddragthemouse.TRANSLATETotranslatetheview,clickandholdthecentermousebuttonanddragthemouse.ZOOMTozoom,clickandholdtherightmousebutton.Tozoomin,dragthemousedown.Tozoomout,dragthemouseup.Inadditiontoyourmouse,therearesixorientingiconslocatedalongtherightsideoftheViewwindow.Toviewthemodelinthe–Xdirection,clicktheicon.Similarly,clickontheothericonstoviewalongtheotherprincipaldirections.Toseetheaxesoftheworldreferenceframe,clicktheaxesiconlocatedontherightsideoftheViewwindow.OpenSim:IntrotoMusculoskeletalModelingPage4CoordinatesTheCoordinateswindowcontainsslidersthatcorrespondtojointcoordinatesinthemodel.ToseetheCoordinateswindow,clicktheWindowmenuandselectCoordinates.Forthecurrentmodel,theorientationofthepelviscorrespondstotheorientationofthemodel.Note:Ifalreadyopened,youcanalsoviewtheCoordinateswindowbyclickingitstitlebar.•ThefirstthreesliderscorrespondtorotationsofthepelvisabouttheZ,X,andY-axesofthe“pelvis”referenceframe.TorotatethepelvisabouttheZ-axis,dragtherZslider.Similarly,torotatethepelvisabouttheothertwoaxes,dragthecorrespondingslider.Note:Theserotationsaredifferentthanrotatingthemodelview.•Theremainingsliderscorrespondtojointrotationsandcontrolasingledegreeoffreedom.Torotatethejoints,dragtheslidersortypeinadesiredjointangleintheadjacenttextbox.•Tosaveapose,oraspecificsetofjointcoordinates,forlateruseinthetutorial:-RestorethedefaultjointcoordinatesbyclickingthePosesbuttonandselectingDefault.-Flextherighthip45ºbytyping45intother_hip_flexiontextboxandpressingEnter.-ClickthePosesbutton,selectNew,typerhipflex45int