Flapping wing actuation using resonant compliant mechanisms

173 Pages·2010·4.99 MB·English

Flapping wing actuation
using resonant compliant
mechanisms
An insect-inspired design

Flapping wing actuation
using resonant compliant
mechanisms
An insect-inspired design
PROEFSCHRIFT
terverkrijgingvandegraadvandoctor
aandeTechnischeUniversiteitDelft,
opgezagvandeRectorMagnificusProf.ir.K.C.A.M.Luyben,
voorzittervanhetCollegevoorPromoties,
inhetopenbaarteverdedigenopdonderdag21oktober2010om12.30uur
door
CasparTitusBOLSMAN
werktuigkundigingenieur
geborenteZaanstad
Ditproefschriftisgoedgekeurddoordepromotor:
Prof.dr.ir.A.vanKeulen
Copromotor:
Dr.ir.J.F.L.Goosen
Samenstellingpromotiecommissie:
RectorMagnificus, voorzitter
Prof.dr.ir.A.vanKeulen, TechnischeUniversiteitDelft,promotor
Dr.ir.J.F.L.Goosen, TechnischeUniversiteitDelft,copromotor
Prof.dr.ir.drs.H.Bijl, TechnischeUniversiteitDelft
Prof.ir.R.H.MunnigSchmidt, TechnischeUniversiteitDelft
Prof.dr.ir.J.L.Herder, UniversiteitTwente
Prof.dr.ir.J.L.vanLeeuwen, WageningenUniversity
Dr.ir. D.Lentink, WageningenUniversity
ThisprojecthasbeenfundedbyTheDevelopmentLaboratories,NWOand
AgentschapNLintheformofaCasimirgrant.
Copyright(cid:2)c 2010byC.T.Bolsman
Allrightsreserved. Nopartofthematerialprotectedbythiscopyrightnotice
maybereproducedorutilizedinanyformorbyanymeans,electronicor
mechanical,includingphotocopying,recordingorbyanyinformationstorage
andretrievalsystem,withoutthepriorpermissionoftheauthor.
ISBN 978-90-9025685-6
Authoremail:
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ForMarieke

Summary
Flapping wing actuation using resonant compliant mechanisms
Aninsect-inspireddesign
This thesis describes the analysis and design of the wing actuation mechanism
for an insect inspired flapping-wing MAV Micro Air Vehicle. Insects are among
nature’s most nimble flyers and are an abundant source of inspiration for the
developmentofflapping-wing MAVs. Thehumanendeavortodesignand realize
flapping wing flight at insect scales has increased in recent years. The focus of
thisthesisisontheexploitationandapplicationofresonantprinciplestoachieve
insect-like wingmovementpatterns. Theinsect thorax-wingsystemisinessence
atunedresonantsystem. Insectsexploitresonancetoreducetheenergyrequired
to realize the wing flapping motion and achieve large amplitude wing motion
by resonant amplitude amplification. The application of resonant principles in
a flapping-wing MAV is intended to achieve the same aspects. The insect wing
movement can be divided into two parts; The first is the flapping motion and
the second is the wing rotation or pitching motion. The research in this thesis
is divided along these lines. The flapping-wing MAV body, which facilitates the
flapping motion is designed separatelybut parallel to the wings, which facilitate
thepitchingmotion.
In order to achieve resonance a significantly flexible structure has to be in-
corporatedintothedesignoftheflapping-wing MAV thorax. Various optionsare
reviewedand anoptionbasedontheuseofbendingischosen. Theelasticstruc-
ture used for the body of the flapping-wing MAV is a ring-type structure. Using
theringinthissettinggivesmanyoptionsforbothwingattachmentandactuator
placement. Theringiscoupledtothewingsbyacompliantamplificationmecha-
nism which transformsand amplifies thering deflectioninto the large wing root
rotation required for the wing flapping motion. The development of the struc-
turesfollowsatwo-stepapproach. Thefirststepistheselectionoffourprototypes
i
ii SUMMARY
used for determining the viability of the structures and proposed analysis meth-
ods, multi-body dynamics models and finite element models. The second set of
structuresisgearedtowardsapplicationleveldetailingandassuchmoreempha-
sis is placed on reducing weight. After initial sizing, the structures are analyzed
byfiniteelements(eigenvalueandtransientanalysis). Basedontheanalysis,the
structureshavebeenbuilt,realizedandtested. Itappearedthatthestructuresare
capableofsustaininglargeamplitudeflappingmotioninaresonantmanner.
The division of the design of the structure allows for independent analysis of
the wings. In insects, the wing pitching motion, which is of paramount impor-
tance for efficient lift production, is predominantly passive in origin. An engi-
neeringequivalentrequiresthepresenceofatunableelasticstructureinthewing
roottofacilitatethepassivewingpitchingmotion. Asolutiontothisproblemhas
been found by adding a simple elastic element in an existing, commonly used,
wing design. The elastic element in the wing root is tuned by using a coupled
quasi-steady aerodynamic and multi-body dynamics model. The reference used
for the tuning is a simplified version of the wing kinematics portrayed by hawk-
moths. Thewingsarerealizedandtestedexperimentallytoseewhetherthewings
reflecttheperformancefoundintheanalysis.
The ring-shaped thorax structure is combined with the wings to test reso-
nant performance of the assembled structure. A test setup is built to quantify
lift production. Lift istestedbysuspendingtheprototypeonaflexiblebeamand
measuring changes in deflection when the model is actuated. Significant lift is
producedusingthecurrentprototype,intheorderoftheweight ofthestructure
withouttheactuator. Kinematicpatternspresentduringresonantactuationshow
correcttimingofwingrotation.
The present developments have led to greater insight in the exploitation of
resonance for driving wings in flapping-wing MAVs. Ring-type structures are a
valid starting point and yield promising results. Further developments lie in the
selectionand tuning ofactuatorsand theincorporationofcontrolpossibilities in
thedesign.
CasparBolsman
Contents
Summary i
1 Introduction 1
1.1 Motivation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 MicroAirVehicles. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 TheAtalantaProject . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4 InspirationfromNature . . . . . . . . . . . . . . . . . . . . . . . . 3
1.5 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.5.1 Whyflappingflight? . . . . . . . . . . . . . . . . . . . . . . 4
1.5.2 Whyinsects? . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.5.3 Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.6 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.6.1 Aim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.6.2 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.7 Thesisstructureandoverview . . . . . . . . . . . . . . . . . . . . . 7
2 Insects 9
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2 Insectanatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2.1 Insectthoraxstructure . . . . . . . . . . . . . . . . . . . . . 11
2.2.2 Wings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.3 Resonanceininsects . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.4 Kinematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.4.1 Rigidbodydescription . . . . . . . . . . . . . . . . . . . . . 18
2.4.2 Bendingandtorsion . . . . . . . . . . . . . . . . . . . . . . 21
2.5 Aerodynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
iii
iv CONTENTS
2.5.1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.6 Concludingremarks . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3 Flapping Wing MAVs 27
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.2 Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.2.1 Overviewofprojects . . . . . . . . . . . . . . . . . . . . . . 28
3.2.2 TheLipcapoweredflapping-wingMAV . . . . . . . . . . . . 28
3.2.3 TheMFIproject . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.2.4 TheHarvardfly . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.2.5 ClappingwingMAVofinsectsize . . . . . . . . . . . . . . . 30
3.2.6 CaltechMicrobat . . . . . . . . . . . . . . . . . . . . . . . . 31
3.2.7 VanderbiltUniversity . . . . . . . . . . . . . . . . . . . . . . 31
3.2.8 GeorgiaTechEntomopter . . . . . . . . . . . . . . . . . . . 32
3.2.9 DelflyMicro . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.2.10 FW-MAV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.2.11 Projectsforreproducingkinematics . . . . . . . . . . . . . . 34
3.2.12 Comparisonofactuationmechanisms . . . . . . . . . . . . 36
3.2.13 Wings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.3 Actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.3.1 Actuatorstypes . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.3.2 Actuatorselectioncriteria . . . . . . . . . . . . . . . . . . . 42
3.3.3 Actuatorcontrol . . . . . . . . . . . . . . . . . . . . . . . . 43
3.3.4 Feasibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.4 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.4.1 Controlinwings . . . . . . . . . . . . . . . . . . . . . . . . 48
3.5 Functionalmechanismrequirements . . . . . . . . . . . . . . . . . 49
4 Conceptual flapping-wing MAV thorax design 51
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.2 Energystorage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.2.1 Deformationmode . . . . . . . . . . . . . . . . . . . . . . . 52
4.2.2 Materialchoice . . . . . . . . . . . . . . . . . . . . . . . . . 53
4.3 Towardsanactuationmechanism . . . . . . . . . . . . . . . . . . . 54
4.4 Concepts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.4.1 Springlikestructures. . . . . . . . . . . . . . . . . . . . . . 56
4.4.2 Coupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.5 Concepts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.5.1 Simpleringbasedstructures. . . . . . . . . . . . . . . . . . 58
4.6 Reviewofconcepts . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.6.1 Comparisonofmechanisms . . . . . . . . . . . . . . . . . . 59
4.7 Extendedconcepts . . . . . . . . . . . . . . . . . . . . . . . . . . . 60