Design-and-Analysis-of-a-Lower-Limb-Rehabilitation

DesignandAnalysisofaLowerLimbRehabilitationRobotXiaohuaShi1,a,HongboWang1,b*,LinYuan1,c,ZhenXu1,d,HongweiZhen1,e,ZengguangHou2,f1CollegeofMechanicalEngineering,YanshanUniversity,Qinhuangdao,066004,China2InstituteofAutomation,ChineseAcademyofScience,Beijing,100080,[e-mail],[e-mail],[e-mail],[e-mail],[e-mail],[e-mail]:Lower-limbrehabilitationrobot,Rehabilitationtraining,Mechanicaldesign.Abstract.Thepaperpresentanewlower-limbrehabilitationrobotwhichconsistsoftwomechanicallegswith3DOF.Thelengthoftwomechanicallegsandtheangleofseatbackoftherehabilitationrobotcanbeadjustedoveracertainrangetofitvariouspatients.Therobotcanexerciseasinglejointormultiplejoints.Ithasthreetrainingmodes:activetraining,passivetrainingandassisttraining.Inordertoevaluatetherehabilitationeffectoftherobot,alljointswereequippedwithtorquesensorsandabsolutepositionencoders.whichisveryimportantforthedesignoftherehabilitationrobot.Besides,therehablitaiontraningcancombinedwithsEMG/FES.Therobotareinstalledbesideachair,thepatientcansitorlieinthechair,whichismorecomfortablethanstandingorsuspending.Theanalysisandexperimentalresultsdemonstratethattheproposedrehabilitationrobotissafeandreliable,theworkspacecanmeetstheneedsofnormalgait.IntroductionTherehabilitationrobotisanewrobotinrecentyears,whichbelongstothecategoryofmedicalrobots.Itincludesrehabilitationtrainingrobotandauxiliaryrehabilitationrobot.Themainfunctionoftherehabilitationtrainingrobotishelpingthepatientstoimproveorrestoreavarietyofmotionfunction,suchasthewalkingtrainingandarmexercisetraining.Accordingtothepowerinputmodetherehabilitationtrainingrobotcanbedividedintotwotypes-legdriveandfootdrive.Theformerdrivesthelegsandthelatterdrivesthefeetofthepatienttocompletegaittraining.Inrecentyears,therearemanyresearchesaboutrehabilitation[1-2].Earlyresearchersinvolvesmusclemovementsandperceptualfeedback,whilelatertreatofFES(Functionalelectricalstimulation)andVirtualReality.TheFESisusingelectricitytostimulatethenervoussystemtorestoremotionanditiswidelyusedinfootdropstimulator.AmechanicalrehabilitationtrainingdevicewassuccessfullydevelopedbyFreeUniversityofBerlin,Germanyin2000,butitdid’tintroducedmoreadvancedservocontrolsystem,neithercansimulatemorecomplexgesture.Soontheinteractivesystemofrehabilitationrobotappeared.Itcanadjustthetrainingmodeandtheartificialintelligentsystemofrobotwasimprovedgreatly[3-7].AgaitrehabilitationtrainingrobotLokomatwasdevelopedbySwiss.Itwasdrivenbyexternalskeletalstructure.Therobotobeysthepreparedgaitcurvetotrain,butthetrainmodeissingle,anditisdifficulttooperate.AnotherrehabilitationrobotSwrotekwasdevelopedinSwiss.Therobothadthreetrainingmodes-active,passiveandassisted,butit’sapplicationwastrouble.Inrecentyears,somedomesticresearchinstitutionssuchasTsinghuaUniversity,SoutheastUniversity,ChineseAcademyofScienceshavebeguntostudyrehabilitationrobot,andachievedgratifyingsuccesses[8-9].MechanicalDesignTheclinicalapplicationrequirementislownoise,friendly,secure,therobotcanbeacceptedbythetherapistandpatients.Bienetal.[10]considerthatthepatientusingtherehabilitationrobotswillnotfeelpainandinconvenience,andtheiractivitieswillnotberestricted.Theaimistomeettheneedsofthepatientsandguidethemtomoveaccordingtothenormalgait,helpthemimproveorrestoretheirmusclestrength.AdvancedMaterialsResearchVols.490-495(2012)pp2236-2240Onlineavailablesince2012/Mar/15at©(2012)TransTechPublications,Switzerlanddoi:10.4028/(ID:8.35.201.39,UniversityofCalifornia,SanDiego,LaJolla,UnitedStatesofAmerica-17/01/14,15:50:41)ChoosetheDOF.Therearethreejointsinlowerlimbincludingthehip,knee,ankleand7DOFofmotionincludinghipflexion/extension,hipadduction/abduction,hippronation/supination,kneeflexor/extensor,kneejointpronation/supination,ankleflexion/extension,anklevarus/valgus.Hipandkneecanrealizecomplexspatialmotion,butthemainmotionisappearinginthesagittalplane.Theothermovementsaretoincreasflexibility,andithaslittlesignificancetotheeffectoftherehabilitationtraining.Therefore,Thelowerlimbissimplifiedasaseriesmechanicalhingewith3DOF,suchashipflexor/extensor,kneeflexion/extension,andankleflexion/extension.Fig.1.MovementrangeofjointsFig.2.ThestructureoffootChooseTheMotionAngle.Inordertoavoidcausingsecondinjuriesintherehabilitationprocess,themotionangleoftherobotjointshouldbeconformedwiththehuman’sjoints.Theinitialstateishorizontalangleof20°,andtherangeofanglesofeachjointisshowninFig.1.Therangeofthehipmotionangleisrelatedwiththepatient’spose,whichmeansthemotionrangeis60°inthesittingpose,andthemotionrangeis80°inthelyingpose.ChooseTheLengthRange.Themechanicallegshouldbeabletoadjusttosuitdifferentleglength.Theremustbecertainproportionalrelationshipbetweenthelengthofthelegandthestature,andthesizeofwomenissmallerthanmen.Wedeterminethelengthrangeofthemechanicallegba