Systems & Control: Foundations & Applications SeriesEditor TamerBas¸ar,UniversityofIllinoisatUrbana-Champaign EditorialBoard KarlJohanA˚stro¨m,LundUniversityofTechnology,Lund,Sweden Han-FuChen,AcademiaSinica,Beijing WilliamHelton,UniversityofCalifornia,SanDiego AlbertoIsidori,UniversityofRome(Italy)and WashingtonUniversity,St.Louis PetarV.Kokotovic´,UniversityofCalifornia,SantaBarbara AlexanderKurzhanski,RussianAcademyofSciences,Moscow andUniversityofCalifornia,Berkeley H.VincentPoor,PrincetonUniversity MeteSoner,Koc¸ University,Istanbul Anthony N. Michel Ling Hou Derong Liu Stability of Dynamical Systems Continuous, Discontinuous, and Discrete Systems Birkha¨user Boston • Basel • Berlin AnthonyN.Michel LingHou DepartmentofElectricalEngineering DepartmentofElectricaland UniversityofNotreDame ComputerEngineering NotreDame,IN46556 St.CloudStateUniversity U.S.A. St.Cloud,MN56301 U.S.A. DerongLiu DepartmentofElectricaland ComputerEngineering UniversityofIllinoisatChicago Chicago,IL60607 U.S.A. MathematicsSubjectClassification:15-XX,15A03,15A04,15A06,15A09,15A15,15A18,15A21, 15A42, 15A60, 15A63, 26-XX, 26Axx, 26A06, 26A15, 26A16, 26A24, 26A42, 26A45, 26A46, 26A48,26Bxx,26B05,26B10,26B12,26B20,26B30,26E05,26E10,26E25,34-XX,34-01,34Axx, 34A12,34A30,34A34,34A35,34A36,34A37,34A40,34A60,34Cxx,34C25,34C60,34Dxx,34D05, 34D10,34D20,34D23,34D35,34D40,34Gxx,34G10,34G20,34H05,34Kxx,34K05,34K06,34K20, 34K30,34K40,35-XX,35Axx,35A05,35Bxx,35B35,35Exx,35E15,35F10,35F15,35F25,35F30, 35Gxx,35G10,35G15,35G25,35G30,35Kxx,35K05,35K25,35K30,35K35,35Lxx,35L05,35L25, 35L30,35L35,37-XX,37-01,37C75,37Jxx,37J25,37N35,39-XX,39Axx,39A11,45-XX,45A05, 45D05,45J05,45Mxx,45M10,46-XX,46Bxx,46B25,46Cxx,46E35,46N20,47-XX,47Axx,47A10, 47B44, 47Dxx, 47D03, 47D06, 47D60, 47E05, 47F05, 47Gxx, 47G20, 47H06, 47H10, 47H20, 54-XX, 54E35, 54E45, 54E50, 70-XX, 70Exx, 70E50, 70Hxx, 70H14, 70Kxx, 70K05, 70K20, 93-XX,93B18,93C10,93C15,93C20,93C23,93C62,93C65,93C73,93Dxx,93D05,93D10,93D20, 93D30 LibraryofCongressControlNumber:2007933709 ISBN-13:978-0-8176-4486-4 e-ISBN-13:978-0-8176-4649-3 Printedonacid-freepaper. (cid:1)c2008Birkha¨userBoston Allrightsreserved.Thisworkmaynotbetranslatedorcopiedinwholeorinpartwithoutthewrit- tenpermissionofthepublisher(Birkha¨userBoston,c/oSpringerScience+BusinessMediaLLC,233 SpringStreet,NewYork,NY10013,USA),exceptforbriefexcerptsinconnectionwithreviewsor scholarlyanalysis.Useinconnectionwithanyformofinformationstorageandretrieval,electronic adaptation,computersoftware,orbysimilarordissimilarmethodologynowknownorhereafterde- velopedisforbidden. Theuseinthispublicationoftradenames,trademarks,servicemarksandsimilarterms,evenifthey arenotidentifiedassuch,isnottobetakenasanexpressionofopinionastowhetherornottheyare subjecttoproprietaryrights. 987654321 www.birkhauser.com (Lap/MP) To our families Contents Preface xi 1 Introduction 1 1.1 DynamicalSystems . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 ABriefPerspectiveontheDevelopmentofStabilityTheory . . . . 4 1.3 ScopeandContentsoftheBook . . . . . . . . . . . . . . . . . . . 6 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2 DynamicalSystems 17 2.1 Notation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2.2 DynamicalSystems . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.3 OrdinaryDifferentialEquations . . . . . . . . . . . . . . . . . . . 20 2.4 OrdinaryDifferentialInequalities. . . . . . . . . . . . . . . . . . . 26 2.5 DifferenceEquationsandInequalities . . . . . . . . . . . . . . . . 26 2.6 DifferentialEquationsandInclusionsDefinedonBanachSpaces . . 28 2.7 FunctionalDifferentialEquations. . . . . . . . . . . . . . . . . . . 31 2.8 VolterraIntegrodifferentialEquations . . . . . . . . . . . . . . . . 34 2.9 Semigroups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 2.10 PartialDifferentialEquations . . . . . . . . . . . . . . . . . . . . . 46 2.11 CompositeDynamicalSystems . . . . . . . . . . . . . . . . . . . . 51 2.12 DiscontinuousDynamicalSystems . . . . . . . . . . . . . . . . . . 52 2.13 NotesandReferences . . . . . . . . . . . . . . . . . . . . . . . . . 59 2.14 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 3 FundamentalTheory: ThePrincipalStabilityandBoundedness ResultsonMetricSpaces 71 3.1 SomeQualitativeCharacterizationsofDynamicalSystems . . . . . 73 3.2 ThePrincipalLyapunovandLagrangeStabilityResultsfor DiscontinuousDynamicalSystems . . . . . . . . . . . . . . . . . . 82 vii viii Contents 3.3 ThePrincipalLyapunovandLagrangeStabilityResultsfor ContinuousDynamicalSystems . . . . . . . . . . . . . . . . . . . 92 3.4 ThePrincipalLyapunovandLagrangeStabilityResultsfor Discrete-TimeDynamicalSystems . . . . . . . . . . . . . . . . . . 103 3.5 ConverseTheoremsforDiscontinuousDynamicalSystems . . . . . 112 3.6 ConverseTheoremsforContinuousDynamicalSystems . . . . . . 125 3.7 ConverseTheoremsforDiscrete-TimeDynamicalSystems . . . . . 133 3.8 Appendix: SomeBackgroundMaterialonDifferentialEquations . . 137 3.9 NotesandReferences . . . . . . . . . . . . . . . . . . . . . . . . . 141 3.10 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 4 FundamentalTheory: SpecializedStabilityandBoundedness ResultsonMetricSpaces 149 4.1 AutonomousDynamicalSystems . . . . . . . . . . . . . . . . . . . 149 4.2 InvarianceTheory . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 4.3 ComparisonTheory . . . . . . . . . . . . . . . . . . . . . . . . . . 158 4.4 UniquenessofMotions . . . . . . . . . . . . . . . . . . . . . . . . 165 4.5 NotesandReferences . . . . . . . . . . . . . . . . . . . . . . . . . 167 4.6 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 5 ApplicationstoaClassofDiscrete-EventSystems 173 5.1 AClassofDiscrete-EventSystems . . . . . . . . . . . . . . . . . . 173 5.2 StabilityAnalysisofDiscrete-EventSystems . . . . . . . . . . . . 175 5.3 AnalysisofaManufacturingSystem . . . . . . . . . . . . . . . . . 176 5.4 LoadBalancinginaComputerNetwork . . . . . . . . . . . . . . . 179 5.5 NotesandReferences . . . . . . . . . . . . . . . . . . . . . . . . . 181 5.6 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 6 Finite-DimensionalDynamicalSystems 185 6.1 Preliminaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 6.2 ThePrincipalStabilityandBoundednessResultsforOrdinary DifferentialEquations . . . . . . . . . . . . . . . . . . . . . . . . . 199 6.3 ThePrincipalStabilityandBoundednessResultsforOrdinary DifferenceEquations . . . . . . . . . . . . . . . . . . . . . . . . . 211 6.4 ThePrincipalStabilityandBoundednessResultsforDiscontinuous DynamicalSystems . . . . . . . . . . . . . . . . . . . . . . . . . . 219 6.5 ConverseTheoremsforOrdinaryDifferentialEquations. . . . . . . 232 6.6 ConverseTheoremsforOrdinaryDifferenceEquations . . . . . . . 241 Contents ix 6.7 ConverseTheoremsforFinite-DimensionalDDS . . . . . . . . . . 243 6.8 Appendix: SomeBackgroundMaterialonDifferentialEquations . . 245 6.9 NotesandReferences . . . . . . . . . . . . . . . . . . . . . . . . . 249 6.10 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253 7 Finite-DimensionalDynamicalSystems: SpecializedResults 255 7.1 AutonomousandPeriodicSystems . . . . . . . . . . . . . . . . . . 256 7.2 InvarianceTheory . . . . . . . . . . . . . . . . . . . . . . . . . . . 258 7.3 DomainofAttraction . . . . . . . . . . . . . . . . . . . . . . . . . 263 7.4 LinearContinuous-TimeSystems . . . . . . . . . . . . . . . . . . 266 7.5 LinearDiscrete-TimeSystems . . . . . . . . . . . . . . . . . . . . 285 7.6 PerturbedLinearSystems . . . . . . . . . . . . . . . . . . . . . . . 295 7.7 ComparisonTheory . . . . . . . . . . . . . . . . . . . . . . . . . . 316 7.8 Appendix: BackgroundMaterialonDifferentialEquationsand DifferenceEquations . . . . . . . . . . . . . . . . . . . . . . . . . 320 7.9 NotesandReferences . . . . . . . . . . . . . . . . . . . . . . . . . 328 7.10 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335 8 ApplicationstoFinite-DimensionalDynamicalSystems 337 8.1 AbsoluteStabilityofRegulatorSystems . . . . . . . . . . . . . . . 338 8.2 HopfieldNeuralNetworks . . . . . . . . . . . . . . . . . . . . . . 344 8.3 DigitalControlSystems. . . . . . . . . . . . . . . . . . . . . . . . 353 8.4 Pulse-Width-ModulatedFeedbackControlSystems . . . . . . . . . 364 8.5 DigitalFilters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 376 8.6 NotesandReferences . . . . . . . . . . . . . . . . . . . . . . . . . 387 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389 9 Infinite-DimensionalDynamicalSystems 395 9.1 Preliminaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396 9.2 ThePrincipalLyapunovStabilityandBoundednessResultsfor DifferentialEquationsinBanachSpaces . . . . . . . . . . . . . . . 398 9.3 ConverseTheoremsforDifferentialEquationsinBanachSpaces . . 408 9.4 InvarianceTheoryforDifferentialEquationsinBanachSpaces . . . 409 9.5 ComparisonTheoryforDifferentialEquationsinBanachSpaces . . 413 9.6 CompositeSystems . . . . . . . . . . . . . . . . . . . . . . . . . . 415 9.7 AnalysisofaPointKineticsModelofaMulticoreNuclearReactor . 420 9.8 ResultsforRetardedFunctionalDifferentialEquations . . . . . . . 423 9.9 ApplicationstoaClassofArtificialNeuralNetworkswithTime Delays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 438 x Contents 9.10 DiscontinuousDynamicalSystemsDeterminedbyDifferential EquationsinBanachSpaces . . . . . . . . . . . . . . . . . . . . . 449 9.11 DiscontinuousDynamicalSystemsDeterminedbySemigroups . . . 463 9.12 NotesandReferences . . . . . . . . . . . . . . . . . . . . . . . . . 479 9.13 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480 Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 486 Index 489 Preface Intheanalysisandsynthesisofcontemporarysystems, engineersandscientistsare frequently confronted with increasingly complex models that may simultaneously includecomponentswhosestatesevolvealongcontinuoustime(continuousdynam- ics)anddiscreteinstants(discretedynamics); componentswhosedescriptionsmay exhibit hysteresis nonlinearities, time lags or transportation delays, lumped param- eters, spatiallydistributedparameters, uncertaintiesintheparameters, andthelike; andcomponentsthatcannotbedescribedbytheusualclassicalequations(ordinary differentialequations,differenceequations,functionaldifferentialequations,partial differential equations, and Volterra integrodifferential equations), as in the case of discrete-eventsystems,logiccommands,Petrinets,andthelike. Thequalitativeanal- ysisofsystemsofthistypemayrequireresultsforfinite-dimensionalsystemsaswell asinfinite-dimensionalsystems;continuous-timesystemsaswellasdiscrete-timesys- tems;continuouscontinuous-timesystemsaswellasdiscontinuouscontinuous-time systems(DDS);andhybridsystemsinvolvingamixtureofcontinuousanddiscrete dynamics. Presently,therearenobooksonstabilitytheorythataresuitabletoserveasasingle sourcefortheanalysisofsystemmodelsofthetypedescribedabove. Mostexisting engineeringtextsonstabilitytheoryaddressfinite-dimensionalsystemsdescribedby ordinary differential equations, and discrete-time systems are frequently treated as analogousafterthoughts,orarerelegatedtobooksonsampled-datacontrolsystems. On the other hand, books on the stability theory of infinite-dimensional dynamical systemsusuallyfocusonspecificclassesofsystems(determined,e.g.,byfunctional differentialequations,partialdifferentialequations,andsoforth). Finally,theliter- atureonthestabilitytheoryofdiscontinuousdynamicalsystems(DDS)ispresently scatteredthroughoutjournalsandconferenceproceedings. Consequently,tobecome reasonablyproficientinthestabilityanalysisofcontemporarydynamicalsystemsof thetypedescribedabovemayrequireconsiderableinvestmentoftime. Thepresent bookaimstofillthisvoid. Toaccomplishthis, thebookaddressesfourgeneralar- eas: therepresentationandmodelingofavarietyofdynamicalsystemsofthetype describedabove;thepresentationoftheLyapunovandLagrangestabilitytheoryfor dynamical systems defined on general metric spaces; the specialization of this sta- bilitytheorytofinite-dimensionaldynamicalsystems;andthespecializationofthis stabilitytheorytoinfinite-dimensionaldynamicalsystems. Throughoutthebook,the applicabilityofthedevelopedtheoryisdemonstratedbymeansofnumerousspecific examplesandapplicationstoimportantclassesofsystems. xi