Lecture Notes in Electrical Engineering 266 Marcin Witczak Fault Diagnosis and Fault-Tolerant Control Strategies for Non-Linear Systems Analytical and Soft Computing Approaches Lecture Notes in Electrical Engineering Volume 266 For furthervolumes: http://www.springer.com/series/7818 About this Series ‘‘Lecture Notes in Electrical Engineering (LNEE)’’is a book series which reports the latest research and developments in Electrical Engineering, namely: • Communication, Networks, and Information Theory • Computer Engineering • Signal, Image, Speech and Information Processing • Circuits and Systems • Bioengineering LNEE publishes authored monographs and contributed volumes which present cutting edge research information as well as new perspectives on classical fields, while maintaining Springer’s high standards of academic excellence. Also con- sidered for publication are lecture materials, proceedings, and other related materials of exceptionally high quality and interest. 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Marcin Witczak Fault Diagnosis and Fault-Tolerant Control Strategies for Non-Linear Systems Analytical and Soft Computing Approaches 123 Marcin Witczak Instituteof ControlandComputation Engineering Universityof Zielona Góra Zielona Góra Poland ISSN 1876-1100 ISSN 1876-1119 (electronic) ISBN 978-3-319-03013-5 ISBN 978-3-319-03014-2 (eBook) DOI 10.1007/978-3-319-03014-2 SpringerChamHeidelbergNewYorkDordrechtLondon LibraryofCongressControlNumber:2013951773 (cid:2)SpringerInternationalPublishingSwitzerland2014 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpartof the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation,broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmissionor informationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodology now known or hereafter developed. Exempted from this legal reservation are brief excerpts in connection with reviews or scholarly analysis or material supplied specifically for the purposeofbeingenteredandexecutedonacomputersystem,forexclusiveusebythepurchaserofthe work. Duplication of this publication or parts thereof is permitted only under the provisions of theCopyright Law of the Publisher’s location, in its current version, and permission for use must always be obtained from Springer. Permissions for use may be obtained through RightsLink at the CopyrightClearanceCenter.ViolationsareliabletoprosecutionundertherespectiveCopyrightLaw. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexempt fromtherelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. While the advice and information in this book are believed to be true and accurate at the date of publication,neithertheauthorsnortheeditorsnorthepublishercanacceptanylegalresponsibilityfor anyerrorsoromissionsthatmaybemade.Thepublishermakesnowarranty,expressorimplied,with respecttothematerialcontainedherein. Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) To my beloved and wonderful wife Anna Preface A permanent increase in the complexity, efficiency and reliability of modern industrial systems necessitates a continuous development in control and fault diagnosis. A moderate combination of these two paradigms is intensively studied under the name offault-tolerant control. This real world’s development pressure hastransformedfaultdiagnosisandfault-tolerantcontrol,initiallyperceivedasthe art of designing a satisfactorily safe system, into the modern science that it is today. Indeed,theclassicwayoffaultdiagnosisboilsdowntocontrollingthelimitsof single variables and then using the resulting knowledge for fault alarm purposes. Apartfromthesimplicityofsuchanapproach,theobservedincreasingcomplexity ofmodernsystemsnecessitatesthedevelopmentofnewfaultdiagnosistechniques. On the other hand, the resulting fault diagnosis system should be suitably inte- grated with the existing control system in order to prevent the development of faults into failures, perceived as a complete breakdown of the system being con- trolled and diagnosed. Suchadevelopmentcanonlyberealisedbytakingintoaccounttheinformation hidden in all measurements. One way to tackle such a challenging problem is to use the so-called model-based approach. Indeed, the application of an adequate modelofthesystembeingsupervisedisveryprofitablewithrespecttogainingthe knowledge regarding its behaviour. A further and deeper understanding of the current system behaviour can be achieved by implementing parameter and state estimation strategies. The obtained estimates can then be used for supporting diagnosticdecisionsandincreasingthecontrolquality,whiletheresultingmodels (along with the knowledge about their uncertainty) can be used for designing suitable control strategies. Although the majority of industrial systems are nonlinear in their nature, the most common approach to settle fault diagnosis and fault-tolerant control prob- lemsistousewell-knowntoolsforlinearsystems,whicharewidelydescribedand well documented in many excellent monographs and books. On the other hand, publications on integrated fault diagnosis and fault-tolerant control for nonlinear systems are scattered over many papers and a number of book chapters. Taking into account the above-mentioned conditions, this book presents selected Fault Diagnosis and Fault-Tolerant Control Strategies for Non-Linear Systems in a unified framework. In particular, starting from advanced state vii viii Preface estimationstrategiesuptomodernsoftcomputing,thediscrete-timedescriptionof thesystemisemployed.Suchachoiceisdictatedbythefactthatthediscrete-time descriptioniseasierandmorenaturaltoimplementonmoderncomputersthanits continuous-timecounterpart.Thisisespeciallyimportantforpracticingengineers, who are hardly ever fluent in complex mathematical descriptions. The book results from my research in the area of fault diagnosis and fault- tolerant control for nonlinear systems that has been conducted since 1998. It is organised as follows. Part I presents original research results regarding state estimation and neural networks for Robust Fault Diagnosis. Part II is devoted to the presentation of integrated fault diagnosis and fault-tolerant systems. It starts with a general fault-tolerant control framework, which is then extended by introducing robustness with respect to various uncertainties. Finally, it is shown how to implement the proposed framework for fuzzy systems described by the well-known Takagi–Sugeno models. This book is primarily a research monograph which presents, in a unified framework, some recent results on fault diagnosis and fault-tolerant control of nonlinear systems. It is intended for researchers, engineers and advanced post- graduate students in control and electrical engineering, computer science, as well as mechanical and chemical engineering. Some of the research results presented in this book were developed with the kind support of the National Science Centre in Poland under the grant No. NN514678440 on Predictive fault-tolerant control for nonlinear systems. Iwouldliketoexpressmysinceregratitudetomyfamilyfortheirsupportand patience.IamalsogratefultoProf.JózefKorbiczforsuggestingtheproblem,and forhiscontinuoushelpandsupport.Iwouldliketoexpressmythankstomyfriends Prof. Vicenç Puig (Universidad Politécnica de Cataluña) and Prof. Christophe Aubrun (Université de Lorraine) for the long lasting and successful cooperation. IalsowouldliketoexpressmyspecialthankstoDr.LukaszDziekanforhishelpin preparing some of the computer programmes, laboratory experiments and simulations ofChap. 6 Zielona Góra, August 2013 Marcin Witczak Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Introductory Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2 Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Part I Robust Fault Diagnosis 2 Unknown Input Observers and Filters . . . . . . . . . . . . . . . . . . . . . 19 2.1 Unknown Input Decoupling . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.2 Preventing Fault Decoupling. . . . . . . . . . . . . . . . . . . . . . . . . . 22 2.3 First- and Second-order Extended Unknown Input Observers . . . 25 2.3.1 Convergence Analysis. . . . . . . . . . . . . . . . . . . . . . . . . 26 2.3.2 Design Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.4 Unscented Kalman Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 2.4.1 Unscented Transform. . . . . . . . . . . . . . . . . . . . . . . . . . 33 2.4.2 Principle of the UKF-Based UIF. . . . . . . . . . . . . . . . . . 34 2.5 Determination of an Unknown Input Distribution Matrix . . . . . . 35 2.6 Design of the UIF with Varying Unknown Input Distribution Matrices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 2.7 Illustrative Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 2.7.1 Estimation of E for an Induction Motor. . . . . . . . . . . . . 43 2.7.2 Varying E Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 2.7.3 Fault Detection and Isolation of a Two-Tank System . . . 47 2.7.4 First- Versus Second-order EUIO . . . . . . . . . . . . . . . . . 53 2.8 Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3 Neural Network-Based Approaches to Fault Diagnosis . . . . . . . . . 57 3.1 Robust Fault Detection with the Multi-Layer Perceptron . . . . . . 58 3.1.1 Illustrative Example . . . . . . . . . . . . . . . . . . . . . . . . . . 63 3.1.2 Algorithms and Properties of D-OED for Neural Networks . . . . . . . . . . . . . . . . . . . . . . . . . . 65 3.1.3 Industrial Application . . . . . . . . . . . . . . . . . . . . . . . . . 78 ix x Contents 3.2 GMDH Neural Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 3.2.1 Model Uncertainty in the GMDH Neural Network . . . . . 84 3.2.2 Bounded-Error Approach. . . . . . . . . . . . . . . . . . . . . . . 86 3.2.3 Synthesis of the GMDH Neural Network Via the BEA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 3.2.4 Robust Fault Detection with the GMDH Model . . . . . . . 93 3.2.5 Alternative Robust Fault Detection Procedure: A Backward Detection Test . . . . . . . . . . . . . . . . . . . . . 95 3.2.6 Industrial Application . . . . . . . . . . . . . . . . . . . . . . . . . 101 3.3 Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 Part II Integrated Fault Diagnosis and Control 4 Integrated Fault Diagnosis and Control: Principles and Design Strategies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 4.1 FTC Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 4.1.1 Fault Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 4.1.2 Stabilisation Problem. . . . . . . . . . . . . . . . . . . . . . . . . . 122 4.1.3 Observer Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 4.1.4 Integrated Design Procedure. . . . . . . . . . . . . . . . . . . . . 123 4.2 Extension to Non-Linear Systems . . . . . . . . . . . . . . . . . . . . . . 125 4.3 Constrained State Estimation . . . . . . . . . . . . . . . . . . . . . . . . . 130 4.3.1 Complete Design Procedure. . . . . . . . . . . . . . . . . . . . . 131 4.4 Application Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 4.4.1 Description of the Twin-Rotor MIMO System . . . . . . . . 132 4.4.2 Non-Linear Reference Model of Twin-Rotor MIMO System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 4.4.3 Fault Scenario 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 4.4.4 Fault Scenario 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 4.4.5 Fault Scenario 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 4.5 Concluding Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 5 Robust H -Based Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 1 5.1 Towards Robust Fault-Tolerant Control . . . . . . . . . . . . . . . . . . 143 5.1.1 Preliminaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 5.1.2 Fault Estimation Approach. . . . . . . . . . . . . . . . . . . . . . 145 5.1.3 Integrated FTC Design . . . . . . . . . . . . . . . . . . . . . . . . 149 5.1.4 Illustrative Example: Fault Estimation. . . . . . . . . . . . . . 151 5.2 Complete Robust Design of Fault-Tolerant Control. . . . . . . . . . 153 5.2.1 Preliminaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 5.2.2 Fault Estimation Strategy. . . . . . . . . . . . . . . . . . . . . . . 154
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