Wei He · Jinkun Liu Active Vibration Control and Stability Analysis of Flexible Beam Systems Active Vibration Control and Stability Analysis of Flexible Beam Systems Wei He Jinkun Liu (cid:129) Active Vibration Control and Stability Analysis of Flexible Beam Systems 123 Wei He Jinkun Liu Schoolof Automation andElectrical Schoolof Automation Science Engineering andElectrical Engineering University of Science andTechnology Beihang University Beijing Beijing,China Beijing,China ISBN978-981-10-7538-4 ISBN978-981-10-7539-1 (eBook) https://doi.org/10.1007/978-981-10-7539-1 JointlyPublishedwithTsinghuaUniversityPress,Beijing,China TheprinteditionisnotforsaleinChinaMainland.CustomersfromChinaMainlandpleaseorderthe printbookfrom:TsinghuaUniversityPress. LibraryofCongressControlNumber:2018953307 ©TsinghuaUniversityPress,BeijingandSpringerNatureSingaporePteLtd.2019 Thisworkissubjecttocopyright.AllrightsarereservedbythePublishers,whetherthewholeorpart of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfrom therelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. Thepublishers,theauthorsandtheeditorsaresafetoassumethattheadviceandinformationinthis book are believed to be true and accurate at the date of publication. Neither the publishers nor the authorsortheeditorsgiveawarranty,expressorimplied,withrespecttothematerialcontainedhereinor for any errors or omissions that may have been made. The publishers remains neutral with regard to jurisdictionalclaimsinpublishedmapsandinstitutionalaffiliations. ThisSpringerimprintispublishedbytheregisteredcompanySpringerNatureSingaporePteLtd. Theregisteredcompanyaddressis:152BeachRoad,#21-01/04GatewayEast,Singapore189721, Singapore Preface Control of flexible beam systems constitutes an important benchmark problem in manyapplicationareas,suchasflexiblemanipulatorsforgrasping,marinemooring lines for station keeping, marine risers for oil transportation, and crane cables for positioning the payload. Flexible systems have a number of advantages such as lightweight,efficiency,higheroperationspeed,andlowercost.Thedynamicsofthe flexiblebeamsystemisessentiallyadistributedparametersystem(DPS).Different from lumped parameter systems, the DPS has an infinite-dimensional state space. The dynamics of DPS modeled by the coupled partial differential equations (PDEs)–ordinary differential equations (ODEs) is difficult to control due to the infinite dimensionality of the beam system. Since the flexible beam system becomes lighter and more flexible, the external disturbances will lead to the mechanical vibrations of flexible beam systems. Therefore, the control strategy should be designed to suppress the vibrations of flexiblebeamsystems.Drivenbypracticalneedsandtheoreticalchallenges,flexible beam systems and their vibration suppression have received great attention. Boundary control is an effective control strategy for vibration suppression of the flexiblebeamsystemwhichisdescribed byhybridPDEs–ODEs.Byusingsensors andactuatorsattheboundary,thedynamicmodelofthesystemisnotaffected,and boundarycontrolcanbederivedfromaLyapunovfunctionwhichisrelevanttothe mechanical energy based on the dynamics of the system. The purpose of this book is to investigate the fundamental issues including dynamic analysis and control design for flexible beam systems by theoretical analysisandnumericalsimulations.Acomprehensivestudyisprovidedtodevelop boundary control methods for the vibration suppression of flexible beam systems with input nonlinearities and output constraint. In addition, the book presents theoretical explorations for advanced control methods of flexible beam systems, includingdistributedcontrol,iterativelearningcontrol,andneuralnetworkcontrol. The control designs are coupled with numerical simulations to illustrate the effectiveness. The book starts with a brief introduction of modeling methods and control techniques for a class offlexible beam systems in Chap. 1. v vi Preface Chapter 2 presents the preliminaries and several lemmas for the subsequent development to simplify the dynamical modeling and further stability analysis for the beam structures, and the dynamic model is also introduced. In Chap. 3, we investigate the boundary control design problem for an Euler– Bernoulli beam model under both the unknown spatiotemporally varying dis- tributed disturbance and time-varying boundary disturbance. The adaptive control laws and disturbance observers are proposed to deal with system parametric uncertainties and external disturbances, respectively. In Chap. 4, the control problem of an Euler–Bernoulli beam with boundary output constraint is addressed. We design a boundary barrier control scheme and apply the proposed Lyapunov function to the original partial differential equations inordertoavoidthespilloverproblem.TheformofLyapunovfunctioncombining boththeintegralLyapunovfunctionandthebarrierLyapunovfunctionisemployed for the control design and stability analysis of the system. In Chap. 5, the largest challenge is how to eliminate the nonlinear input satu- ration characteristic and to design an effective active control law for the flexible beam system. We propose the hyperbolic tangent function in the control design of the flexible system to reduce the influence induced by the input saturation. In Chap. 6, the boundary control architecture is proposed for continuous-time PDEsystemsprecededbyinputdead-zonenonlinearity.Byusinganewdescription of the dead-zone, boundary control schemes are developed to regulate the defor- mation of Euler–Bernoulli beam system even in the presence of the external dis- turbance.Itisprovedthattheproposedcontrollawcanensureuniformlyultimately boundness of the entire system and achieve stabilization. InChap.7,wediscussaproblemofaflexiblebeamsystemwithinputbacklash characteristic. By transforming the nonlinear input backlash to linear input, the boundary control law and disturbance observer are designed at the top offlexible beamviaconstructingaLyapunovcandidatefunctiontoreducethevibrationofthe system. The transverse displacement of the closed-loop system is proved to con- verge to a small neighborhood of zero. In Chap. 8, we present the control design for the flexible Euler–Bernoulli beam system with global constraint and uncertain tip payload. To prevent the constraint violation,theintegralbarrierLyapunovfunctionisemployedforthecontroldesign andstabilityanalysis.Weproposeadistributedcontrolsothatthedeflectionofthe mechanical system can track the desired signal. Exponential stability is well achieved without violation of the constraint. InChap.9,weproposeanadaptiveboundaryiterativelearningcontrol(ABILC) scheme for an Euler–Bernoulli beam system with an aperiodic distributed distur- bance, an aperiodic boundary disturbance, and an unknown system parameter. In order to tackle the input saturation, a hyperbolic tangent function and a saturation function are utilized. Three adaptive laws are proposed and learned along the iteration axis. Based on a time-weighted Lyapunov–Krasovskii-like composite energyfunction,therestrainedABILClawisdesigned.Fortheclosed-loopsystem, the boundedness of all the signals in each iteration is guaranteed. Along the Preface vii iteration axis, the displacements converge to zero in the presence of the external disturbances. In Chap. 10, in order to analyze the flexible beam structure, the assumed mode method (AMM) is employed to develop the dynamic model. Based on the N-dimensional discrete dynamic model, neural network control is investigated to track the desired trajectory accurately and to suppress the flexible vibration maxi- mally.Toensurestabilityrigorouslyasthegoal,thesystemisprovedtobeuniform ultimate boundedness (UUB) by Lyapunov stability method. Eventually, simula- tions verify that the proposed control strategy is effective. In Chap. 11, a model of a coupled three-dimensional flexible beam with a tip payload is derived by using Hamilton principle and described by a set of partial differentialequationsandordinarydifferentialequations.Boundarycontrollawsare proposed to suppress the vibration of the beam in both longitudinal and transverse directions with the environmental disturbance, and the uniform boundedness and theuniformlyultimateboundednessoftheclosed-loopsystemareproved.Adaptive control laws are proposed to overcome the uncertainty of the tip payload, and the uniform boundedness and the uniformly ultimate boundedness of the system are proved. In Chap. 12, the conclusions are summarized and the future works are given. In summary, this book covers the dynamical analysis and control design for flexiblebeamsystems.Thebookisprimarilyintendedforresearchersandengineers in the control system. It can also serve as a complementary reading on modeling and control offlexible beam systems at the postgraduate level. Beijing, China Wei He Jinkun Liu Acknowledgements For this book, we have had the great fortune of working with brilliant people who are generous with their time and friendship, through many discussions filled with creativityandinspiration.Firstofall,wewouldliketoexpressourgratitudetoour co-workers who have contributed to the collaborative studies of this book. We would also like to express our sincere appreciation to our colleagues who havecontributedtothecollaborativeresearch.Inparticular,wewouldliketothank Shuzhi Sam Ge, from the National University of Singapore, Singapore; Miroslav Krstic, from the University of California, San Diego, US; Khac Duc Do, from the Curtin University, Australia; Keum-Shik Hong, from the Pusan National University, Korea; Bao-Zhu Guo, from the Academy of Mathematics and Systems Science, Chinese Academy of Sciences, China; Huai-Ning Wu, from the Beihang University,China;Jun-MinWang,fromtheBeijingInstituteofTechnology,China, and their research groups for their excellent research works, and helpful advice on ourresearch.SpecialthanksgotoDongliangShengforhisassistanceandeffortson the process of publishing this book. Appreciations must be made to Xiuyu He, Yuhua Song, Tingting Meng, Kai Huang, Hejia Gao, Zhe Jing, Weijie Xiang, Hui Qin, Hoang Minh Vu, Yu Liu, Zhijia Zhao, Zhijie Liu, Yuncheng Ouyang, Linghuan Kong, Xinling Yue, Jiali Feng, and Qingyu Zhou for the constructive discussions and sharing of ideas. ThisworkissupportedbytheNationalKeyResearchandDevelopmentProgram ofChina under Grant 2017YFB1300102, theNationalNaturalScience Foundation of China under Grant 61522302, 61873298, 61761130080, the Newton Advanced Fellowship from The Royal Society, UK, under Grant NA160436, the Beijing Natural Science Foundation under Grant 4172041, and the Fundamental Research FundsfortheChinaCentral UniversitiesofUSTBunder GrantFRF-BD-17-002A. Haidian District, Beijing, China Wei He Jinkun Liu ix Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Background and Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Application of Flexible Beam Systems. . . . . . . . . . . . . . . . . . . 3 1.3 Conventional Modelling Methods . . . . . . . . . . . . . . . . . . . . . . 8 1.3.1 Modeling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.3.2 Model Discretization . . . . . . . . . . . . . . . . . . . . . . . . . 10 1.4 A Brief Survey of Control Approaches . . . . . . . . . . . . . . . . . . 11 1.4.1 Implementation Location . . . . . . . . . . . . . . . . . . . . . . 11 1.4.2 Control Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1.5 Outline of the Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2 Mathematical Preliminaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.1 The Hamilton Principle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.2 Lyapunov Stability Theorem . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.3 Useful Lemmas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.4 Modeling of a Flexible Beam System . . . . . . . . . . . . . . . . . . . 28 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 3 Vibration Control of a Flexible Beam. . . . . . . . . . . . . . . . . . . . . . . 33 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.2 Problem Formulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 3.3 Control Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.3.1 Robust Boundary Control with a Disturbance Observer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.3.2 Adaptive Boundary Control with the System Parametric Uncertainties . . . . . . . . . . . . . . . . . . . . . . . 45 3.4 Numerical Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 3.5 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 xi xii Contents 3.6 Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 4 Vibration Control of a Flexible Beam with Output Constraint. . . . 59 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 4.2 Control Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 4.2.1 Model-Based Boundary Control . . . . . . . . . . . . . . . . . 61 4.2.2 Adaptive Boundary Control . . . . . . . . . . . . . . . . . . . . 65 4.3 Numerical Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 4.4 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 5 Vibration Control of a Flexible Beam with Input Saturation . . . . . 75 5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 5.2 Problem Formulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 5.3 Control Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 5.4 Numerical Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 5.5 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 6 Vibration Control of a Flexible Beam with Input Dead-Zone . . . . . 85 6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 6.2 Problem Formulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 6.3 Control Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 6.4 Numerical Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 6.5 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 7 Vibration Control of a Flexible Beam with Input Backlash . . . . . . 97 7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 7.2 Problem Formulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 7.3 Control Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 7.4 Numerical Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 7.5 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 8 Distributed Control of a Flexible Beam. . . . . . . . . . . . . . . . . . . . . . 113 8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 8.2 Problem Formulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 8.3 Control Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 8.4 Numerical Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 8.5 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124