Myoelectric Prosthesis - Modelization and Control of a Bionic Arm

101 Pages·2015·10.76 MB·English

FACULDADE DE ENGENHARIA DA UNIVERSIDADE DO PORTO
Myoelectric Prosthesis - Modelization
and Control of a Bionic Arm
Rafael de Castro Aguiar
MestradoIntegradoemEngenhariaEletrotécnicaedeComputadores
Supervisor: Prof. FernandoLoboPereira
April15,2015
(cid:13)c RafaelAguiar,2015

Abstract
This project concerns the analysis, modeling and control of a prosthetic arm, by means of
Electromyographic signals. The social need to fight adversity continuously allows dedicated and
innovative studies that aim to achieve new and improved solutions to fight disabilities. The con-
nectionbetweentheBiomedical,MechanicalandElectricalEngineeringfieldsbecomesmoreev-
ident, with countless researchers presenting their new ideas and projects in the various fields of
biomechatronics.
The project begins with an initial study on the state-of-the-art technologies concerning myo-
electric acquisition and processing, and respective control of prosthetic devices. Associated with
this study, comes the need to analyze how a real human arm functions, the respective ranges of
motion, degrees of freedom, relative weight and segment lengths and normal behaviors in spe-
cificcasestudies. Thisleadstothedesignofasomewhatanthropomorphicmodelinasimulation
environment, enabling the replication of the natural limb, by resorting to the Denavit Hartenberg
convention for kinematic and dynamic studies, close to those used for normal robotic manipula-
tors.
Another critical feature of this project is to provide a human like behaviour to the simulated
limb. Todoso, theneedtostudydifferentcontroldesignsystemsisrequired. NotionsofHybrid
Systems,NonlinearControlandModelPredictiveControl(MPC)areintroduced,toolsthatcanin
factprovidethedesiredclassesofmotion. TheselectedcontrolarchitectureisbasedonMPC,that
hasthecapacitytonotonlyadaptitsinputsbutitsreferencesitself.
Thedesignedsystemconsistsinamultilayeredcontrolarchitecture,takingintoconsideration
the human and mechanical constraints, exhibiting 3 separate layers: Motion Planning, Motion
Coordination andLow Level MotionExecution Control. The MotionPlanning layer receivesthe
processedEMGsignalandgeneratesaconcatenatedsetofsubreferencesoftheintendedmotion
to be executed. The Motion Coordination layer will include the devised specific MPC adapted
controller and adjust the references generated by the higher level. Lastly, the Low Level Motion
ExecutionControlprovidesallthesubsystemswiththepre-processedreferencesprovidedbythe
MPC.Withthisarchitecture,thesystemprovidesanextremely"human-like"motionbyallowing
itselfseveralreplanningandadjustingstages.
Severaldifferentapproachesandredesignsofthecontrolarchitectureandarmmodelareper-
formed. A simulation environment is designed to test a 3 degree of freedom arm model (tran-
shumeral type prosthetic), whichreceives a motion command froma simple control system. The
results are compared to a specific case study of a natural, healthy limb with the same movement
pattern, yielding a positive response to external disturbances. Due to the limited scope of this
project, not all subsystems of the Control Architecture were able to be tested, remaining on a
designstage,awaitingfurtherdevelopments.
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Agradecimentos
Antesdetudomais,aoProfessorFernandoLoboPereira,porterouvidoumapequenaideiae
terajudadotãofortementeadesenvolvereorientarumfantásticoprojetoqueapenasemsonhose
encontrava.
E neste longo percurso, várias foram as fontes de inspiração e ombros amigos que me supor-
taram,ouviramechoraram/riramameulado. NuncaespereisertãobemrecebidonoLaboratório
I-109 (Robis) no meio de investigadores fantásticos, de técnicos experientes e de ter saído com
inúmeroseincalculáveisamigosementores.
Vários são os nomes que gostaria de mencionar ao longo destes meses, porém acho mere-
ceremdestaquealgunsdosquemaisme"aturaram". AtiDaniel,pelatuaforteamizadeeporme
introduzireseencaminharesnestepequenomundopóscurso.
A ti Jorge e a si Sr. Fernando, por me guiarem e instruírem num mundo técnico para mim
novo,pelashistóriasfantásticasesessõesde"treino"quemefacultaram.
AtiHébereatiFilipe,porolharemparamimcomoummiúdoqueprecisavadeajudaelogo
prontificarem os vossos conselhos, fornecendo também aquela motivação extra no dia-a-dia com
aconstantepergunta"Jáestáescrita?".
AtiDiana,portodaatuaajuda,portodooteuconhecimentoepelatuaamizadefantástica. E
atiminhanovairmãGraça,pelosorrisoquemeconseguiasdartodososdias.
Aosmeuspaiseirmãos,maioresfontesdeinspiraçãodaminhavidaealicercesdetodoomeu
sucesso.
Andlast,butnotleast,toyouCécile. Yourwordsandloveguidemethroughthegreyestdays
andgivemethatneededembertocarryonandachievewhateverdreamIhave.
RafaeldeCastroAguiar
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"Oneman’s’magic’isanotherman’sengineering”
RobertA.Heinlein
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