Design, Modeling and Experiments of 3-DOF Electromagnetic Spherical Actuators

186 Pages·2011·5.88 MB·English

by  Liang Yan

Design, Modeling and Experiments of 3-DOF
Electromagnetic Spherical Actuators
MECHANISMS AND MACHINE SCIENCE
Volume4
SeriesEditor
MARCOCECCARELLI
Forothertitlespublishedinthisseries,goto
www.springer.com/series/8779
Liang Yan (cid:2) I-Ming Chen (cid:2) Chee Kian Lim (cid:2)
Guilin Yang (cid:2) Kok-Meng Lee
Design, Modeling
and Experiments
of 3-DOF
Electromagnetic
Spherical Actuators
LiangYan GuilinYang
BeihangUniversity SingaporeInstitute
SchoolofAutomationScience ofManufacturingTechnology
andElectricalEngineering NanyangDrive71
100191Beijing 638075Nanyang
People’sRepublicofChina Singapore
[email protected] [email protected]
I-MingChen Kok-MengLee
NanyangTechnologicalUniversity GeorgiaInstituteofTechnology
SchoolofMechanicalandAerospace 30332-0405Atlanta
Engineering USA
639798Singapore [email protected]
Singapore
[email protected]
CheeKianLim
SingaporePolytechnic
SchoolofMechanical&Aeronautical
Engineering
500DoverRoad
139651Singapore
Singapore
[email protected]
ISSN2211-0984 e-ISSN2211-0992
ISBN978-94-007-1645-2 e-ISBN978-94-007-1646-9
DOI10.1007/978-94-007-1646-9
SpringerDordrechtHeidelbergLondonNewYork
LibraryofCongressControlNumber:2011930839
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The bookisdedicatedtoauthors’ families.

Preface
Learningwithoutthoughtislaborlost;thoughtwithoutlearningisperilous.
–Confucius(551-479BC)
Motors and actuators producing one degree-of-freedom (DOF) rotary or lin-
ear motion have been the main driving elements of modern machinery for a long
time.Withtheadvancementoftechnology,moreandmorenewmachinespossess-
ing complex structures and sophisticate motions to achieve tasks that have never
beenautomatedbeforehavebeendeveloped,forexample,humanoidrobots,surgi-
calrobots,electricvehicles,justtonameafew.Inordertohaveacompactdesign
ofthemachinery,actuatorsthatcanproducemultipledegreesoffreedommotionin
oneintegratedpackagewithouttheintermediatetransmissionmechanismsbecome
crucial. However, there are quite a few technical challenges to realize a multiple
DOFactuatoratpresent.First,investigationoftheactuatingprincipleformultiple
DOFmotionswithloadbearingcapabilitylikeorgreaterthanthehumanisneces-
sary. There are very few types of actuators that can achieve the load density com-
parabletothatofthehuman.Thedesignoftheloadbearingstructureformultiple
DOFmotionisanotherimportantfactor.OneDOFrotaryorlinearmotorscanrun
smoothlyandpreciselywithreadilyavailableprecisionrotaryandlinearbearings.
Itisnotpossibletofindsuchcomponentformulti-DOFactuatorsatpresent.Ifpre-
cisemotioncontrolisrequiredforsuchmulti-DOFactuators,sensorsthatcandetect
themultipleDOFrotormotionarenecessity.Hence,multi-DOFsensingtechnology
becomespartoftheworkfortherealizationoftheactuator.
Spherical motion is a compact multi-DOF rigid body motion along a spherical
surface with permanent center of rotation. By examining the machinery and sys-
temssurroundedus,sphericalmotioncouldpossiblybethesecondmostimportant
motiontypenexttothecompactrotarymotion.Biologicalsystemsexampleswith
spherical motions can be found in the eyeball movements, human wrist, shoulder,
vii
viii Preface
andhipjointmotions.Industrialexamplescanbefoundinthesurveillancedevices,
automationtools,automobiles,andhomeappliances.Existingsphericalmotiongen-
erationdevicesarefrequentlydesignedbycombiningtwotothreerotaryactuators
with serially or parallel connected mechanisms. Such devices are inevitably bulky
anddifficulttobedeployedasacriticalcomponentincomplexmachinery.There-
fore, the need to develop a multiple DOF actuator capable of generating spherical
motionarises.
The theme of this monograph is on the development of a compact electromag-
neticsphericalactuatorthatcanproducetwoorthreedegreesofsphericalmotion.
Through the study of this spherical actuator, the challenges of designing a multi-
DOFactuatormentionedabovearetobeaddressed.Sphericalactuatorsbasedona
number of actuating principles such as electromagnetic force, piezoelectricity and
mechanical means, have been explored by researchers. Electromagnetic actuation
principle is chosen because of the load density, abundance of the material, and its
compatibilitywithexistingsingleDOFmotorswidelyavailableatpresent.Theun-
derlyingactuatordesignisaball-jointstructurewitharotorandastator.Therotor
iscapableofmovingindifferentorientationswithfiniteanglesorfull360degrees
about a fixed point within the actuator. It is our hope that the spherical actuator
designed in this manner can be accepted and adopted by the industry based on its
noveltyaswellasitscompatibilityandresemblancewithexistingmotorsinterms
oftheactuatingprincipleandcontrol.
Thismonographpresentsagenericmethodologyonmodeling,designandexperi-
mentalinvestigationon3-DOFpermanentmagnet(PM)sphericalactuators.Apara-
metricdesignapproachisadoptedfromthecoilandpolelayout,sphericalmagnetic
fieldstrengthtothemotortorque-currentfunction.Thisapproachoffersresearchers
andengineerstodesignthesphericalactuator,suchasthepoleconfigurationsand
structureparameters,basedonspecificrequirementsfromtheapplications.Further-
more,theactuatordesigncanbefine-tunedandoptimized,whichisoftenrequired
incomplexsystemdesign.Thetopicsinthisbookcovertheintroductionofdifferent
typesofsphericalactuators,formulationofthree-dimensional(3D)sphericalmag-
neticfield,analyticalmotortorquemodeling,prototypedevelopment,experimental
investigationonmagneticfieldandmotortorque,and3Dorientationsensingtech-
niques.
Whilethisbookisprimarilyintendedforresearchersanddevelopersworkingon
spherical actuators, sensors and instruments, we also hope that it will interest re-
searchers and students working in the area of electric machinessince the methods
proposedcouldalsobeusefulfortheunderstandingandanalysisofotherselectro-
magnetic actuators; people in the area of magnetic field analysis since this book
is also an illustrative example of the modeling and analysis of complex magnetic
fields;peopleintheareaofsensorssincethisbookprovidesasolidstartingpointfor
thebasicconceptandworkingprincipleofvariousorientationmeasurementmeth-
ods.Itisalsoourhopethatthisbookcouldprovideasteppingstoneforgreatertech-
nology advancement in multi-DOF actuator design as future applications of these
actuatorsareabundant.
Preface ix
This book is a complete exposition of the research work accomplished by the
authorsontheelectromagneticsphericalactuatorsovertheyearsthroughresearch
collaborationamongtheNanyangTechnologicalUniversity(Singapore),Singapore
InstituteofManufacturingTechnology,andGeorgiaInstituteofTechnology(USA).
Theauthorssincerelyappreciatetheinstitutionalsupportreceivedfromthethreeor-
ganizations.ThemajorportionsofthebookwerebasedonthePhDdissertationsof
two authors, Liang Yan and Chee Kian Lim while studying at Nanyang Techno-
logical University. Part of the work on orientation sensing for spherical actuators
receivedgraduatestudentmanpowersupportfromChinaScholarshipCouncil.This
book would not have been possible without the help and the support from many
people.Inparticular,wewouldliketothankDr.WeiLinforthefinancialsupport,
Mr. Jialin Su for valuable technical comments, Prof. Weihai Chen, Prof. Yunhua
Li,Dr.ZhongweiGuoandDr.YanLangforthedesignandconstructionoftheex-
perimentalapparatusandtheactuatorcontrolsystem,andThomasMoongfordata
collection,incarryingouttheresearchprojectandsubsequentlycompletionofthis
book.Deepappreciationsfromtheauthorsalsogotoseveralformermembersofthe
RoboticsResearchCenterofNanyangTechnologicalUniversity,especiallyYanJin
andXueyanTangforanumberoffiguresinthisbook.Theauthorsaregratefulto
theirfamilieswhosepatienceandcomprehensionhavepermittedthemtospendtime
andeffortonelaboratingandcompletingthisbook.Finally,theauthorswouldalso
liketoacknowledgethesupportfromtheAgencyforScience,TechnologyandRe-
search(A*STAR)ofSingapore,theNationalNatureScienceFoundationofChina,
andtheFundamentalResearchFundsfortheCentralUniversities,China.
December2010 Singapore,Beijing,andAtlanta