Diagnosis and Fault-tolerant Control 2 SCIENCES Systems and Industrial Engineering, Field Director – Jean-Paul Bourrières Reliability, Diagnosis, Safety and Maintenance of Systems, Subject Head – Jean-Marie Flaus Diagnosis and Fault-tolerant Control 2 From Fault Diagnosis to Fault-tolerant Control Coordinated by Vicenç Puig Silvio Simani First published 2021 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc. Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address: ISTE Ltd John Wiley & Sons, Inc. 27-37 St George’s Road 111 River Street London SW19 4EU Hoboken, NJ 07030 UK USA www.iste.co.uk www.wiley.com © ISTE Ltd 2021 The rights of Vicenç Puig and Silvio Simani to be identified as the authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988. Library of Congress Control Number: 2021941902 British Library Cataloguing-in-Publication Data A CIP record for this book is available from the British Library ISBN 978-1-78945-059-0 ERC code: PE7 Systems and Communication Engineering PE7_1 Control engineering Contents Chapter1.NonlinearMethodsforFaultDiagnosis . . . . . . . . . . . 1 SilvioSIMANIandPaoloCASTALDI 1.1.Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2.Faultdiagnosistasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2.1.Residualgenerationtask . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2.2.Residualevaluationtask . . . . . . . . . . . . . . . . . . . . . . . . 8 1.3.Model-basedfaultdiagnosis . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.3.1.Parityspacerelations. . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.3.2.Observer-basedapproaches . . . . . . . . . . . . . . . . . . . . . . 12 1.3.3.Nonlinearfilteringmethods . . . . . . . . . . . . . . . . . . . . . . 14 1.3.4.Nonlineargeometricapproachstrategy . . . . . . . . . . . . . . . 17 1.4.Data-drivenfaultdiagnosis . . . . . . . . . . . . . . . . . . . . . . . . . 20 1.4.1.Onlineidentificationmethods . . . . . . . . . . . . . . . . . . . . . 21 1.4.2.Machinelearningapproachestofaultdiagnosis. . . . . . . . . . . 24 1.5.Model-basedanddata-drivenintegratedfaultdiagnosis . . . . . . . . . 34 1.6.Robustfaultdiagnosisproblem . . . . . . . . . . . . . . . . . . . . . . . 42 1.7.Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 1.8.References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Chapter2.LinearParameterVaryingMethods . . . . . . . . . . . . . . 57 MickaelRODRIGUES,HabibHAMDIandDidierTHEILLIOL 2.1.Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 2.2.Preliminaries: aclassicalapproach . . . . . . . . . . . . . . . . . . . . . 60 2.3.Problemstatement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 2.4.Robustactivefault-tolerantcontroldesign . . . . . . . . . . . . . . . . . 65 2.4.1.Robustobserver-basedFTCdesign. . . . . . . . . . . . . . . . . . 65 2.4.2.Stabilityanalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 vi DiagnosisandFault-tolerantControl2 2.5.Application: ananaerobicbioreactor . . . . . . . . . . . . . . . . . . . . 75 2.6.Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 2.7.References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Chapter3.FuzzyandNeuralNetworkApproaches . . . . . . . . . . . 85 MarcinWITCZAK,MarcinPAZERA,NorbertKUKUROWSKIand MarcinMRUGALSKI 3.1.Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 3.2.Fuzzymodeldesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 3.2.1.Takagi–Sugenosystems . . . . . . . . . . . . . . . . . . . . . . . . 87 3.2.2.GenerationofTSmodelsvianonlinearembedding. . . . . . . . . 88 3.3.Neuralmodeldesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 3.3.1.Recurrentneuralnetwork . . . . . . . . . . . . . . . . . . . . . . . 90 3.3.2.Identificationoftheneuralmodeluncertainty . . . . . . . . . . . . 93 3.4.Faultestimationanddiagnosis . . . . . . . . . . . . . . . . . . . . . . . 94 3.4.1.Actuatorfaultestimationusingneuralnetworks . . . . . . . . . . 94 3.4.2.Sensorandactuatorfaultestimationusingfuzzylogic . . . . . . . 97 3.5.Fault-tolerantcontrol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 3.5.1.Anoverviewofthefault-tolerantscheme . . . . . . . . . . . . . . 101 3.5.2.Robustfaultestimationandcontrol. . . . . . . . . . . . . . . . . . 103 3.5.3.Derivationofarobustinvariantset . . . . . . . . . . . . . . . . . . 106 3.5.4.EfficientpredictiveFTC . . . . . . . . . . . . . . . . . . . . . . . . 106 3.6.Illustrativeexamples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 3.6.1.Sensorandactuatorfaultestimationexample . . . . . . . . . . . . 110 3.6.2.Fault-tolerantcontrolexample . . . . . . . . . . . . . . . . . . . . 113 3.7.Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 3.8.Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 3.9.References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 Chapter4.ModelPredictiveControlMethods . . . . . . . . . . . . . . 121 KrzysztofPATAN 4.1.Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 4.2.IdeaofMPC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 4.3.RobustnessofMPC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 4.4.Neural-network-basedrobustMPC . . . . . . . . . . . . . . . . . . . . . 126 4.4.1.Neuralnetworkmodels . . . . . . . . . . . . . . . . . . . . . . . . 127 4.4.2.NonlinearMPC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 4.4.3.ApproximateMPC . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 4.4.4.RobustnonlinearMPC. . . . . . . . . . . . . . . . . . . . . . . . . 132 4.4.5.RobustapproximateMPC . . . . . . . . . . . . . . . . . . . . . . . 132 4.5.Robustcontrolofapneumaticservo . . . . . . . . . . . . . . . . . . . . 134 4.5.1.Robustnonlinearneural-network-basedMPC . . . . . . . . . . . . 135 4.5.2.Robustapproximateneural-network-basedMPC . . . . . . . . . . 139 Contents vii 4.6.Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 4.7.References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 Chapter5.NonlinearModelingforFault-tolerantControl . . . . . . . 143 SilvioSIMANIandPaoloCASTALDI 5.1.Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 5.1.1.Jointfaultdiagnosisandcontrol . . . . . . . . . . . . . . . . . . . 147 5.1.2.Nonlinearadaptivefaultestimators. . . . . . . . . . . . . . . . . . 149 5.1.3.Fuzzyfault-tolerantcontrol . . . . . . . . . . . . . . . . . . . . . . 161 5.1.4.Recursiveadaptivecontrol . . . . . . . . . . . . . . . . . . . . . . 164 5.1.5.Sustainablecontrol . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 5.2.Fault-tolerantcontrolstrategies . . . . . . . . . . . . . . . . . . . . . . . 175 5.2.1.Faulttoleranceandcompensation . . . . . . . . . . . . . . . . . . 177 5.3.Faultdiagnosisandtolerantcontrol. . . . . . . . . . . . . . . . . . . . . 180 5.3.1.Fault-tolerantcontroldesign . . . . . . . . . . . . . . . . . . . . . 183 5.4.Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186 5.5.References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 Chapter6.VirtualSensorsandActuators . . . . . . . . . . . . . . . . . 193 DamianoROTONDOandVicençPUIG 6.1.Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 6.2.Problemstatement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 6.3.Virtualsensorsandvirtualactuators . . . . . . . . . . . . . . . . . . . . 198 6.4.LMI-baseddesign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202 6.5.Additionalconsiderations . . . . . . . . . . . . . . . . . . . . . . . . . . 205 6.6.Applicationexample . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208 6.6.1.Virtualactuator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 6.6.2.Virtualsensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 6.7.Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212 6.8.References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212 Chapter7.Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 VicençPUIGandSilvioSIMANI 7.1.Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 7.2.Closingremarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 7.3.References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 Chapter8.OpenResearchIssues . . . . . . . . . . . . . . . . . . . . . . 241 VicençPUIGandSilvioSIMANI 8.1.Furtherworksandopenproblems. . . . . . . . . . . . . . . . . . . . . . 241 8.1.1.Sustainablecontroldesignobjectives . . . . . . . . . . . . . . . . 243 8.1.2.Sustainablecontrolconceptsandapproaches . . . . . . . . . . . . 247 viii DiagnosisandFault-tolerantControl2 8.1.3.Sustainablecontrolapproachesandworkingmethods . . . . . . . 249 8.1.4.Sustainablecontroldesignambition . . . . . . . . . . . . . . . . . 253 8.1.5.Sustainablecontrolinnovationpotentials . . . . . . . . . . . . . . 258 8.1.6.Sustainablecontrolexpectedimpacts . . . . . . . . . . . . . . . . 259 8.2.Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261 8.3.References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262 ListofAuthors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 SummaryofVolume1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 1 Nonlinear Methods for Fault Diagnosis Silvio SIMANI1 andPaolo CASTALDI2 1DepartmentofEngineering,UniversityofFerrara,Emilia-Romagna,Italy 2DepartmentofElectrical,ElectronicandInformationEngineering, UniversityofBologna,Italy 1.1. Introduction The model-based approach to fault diagnosis in technical processes has been receivingmoreandmoreattentionoverthelastfourdecades,inthecontextsofboth researchandrealplantapplication. Stemming from this activity, a large number of methods can be found in current literature based on the use of mathematical models of the technical process under diagnosisandonexploitingadvancedcontroltheory. Model-based fault diagnosis methods usually use residuals that indicate changes betweentheprocessandthemodel.Onegeneralassumptionisthattheresidualsare changed significantly so that detection is possible. This means that the residual size aftertheappearanceofafaultislargeandlongenoughtobedetectable. This chapter provides an overview on different fault diagnosis strategies, with particular attention to the fault detection and isolation (FDI) methods related to the dynamicprocessesandapplicationexamplesconsideredinthisbook. Forallofthemethodsconsidered,itisessentialthatthetechnicalprocesscanbe described by a mathematical model. As there is almost never an exact agreement DiagnosisandFault-tolerantControl2, coordinatedbyVicençPUIGandSilvioSIMANI.©ISTELtd2021. Diagnosis and Fault-tolerant Control 2: From Fault Diagnosis to Fault-tolerant Control, First Edition. Vicenç Puig and Silvio Simani. © ISTE Ltd 2021. Published by ISTE Ltd and John Wiley & Sons, Inc. 2 DiagnosisandFault-tolerantControl2 between the model used to represent the process and the plant, the model-reality discrepancyisofprimaryinterest. Hence, the most important issue in model-based fault detection concerns the accuracy of the model describing the behavior of the monitored system. This issue has become a central research theme over recent years, as modeling uncertainty has risen from the impossibility of obtaining complete knowledge and understanding of themonitoredprocess. The main focus of this chapter is the mathematical description aspects of the process whose faults are to be detected and isolated. The chapter also studies the general structure of the controlled system, its possible fault locations and modes. Residual generation is then identified as an essential problem in model-based FDI, because, if it is not performed correctly, some fault information could be lost. The generalframeworkfortheresidualgenerationisalsorecalled. Residual generators based on different methods, such as input–output, state and outputobservers,parityrelationsandparameterestimations,arejustspecialcasesin this general framework. In the following, some commonly used residual generation and evaluation techniques are discussed and their mathematical formulation is presented. Finally, the chapter presents and summarizes special features and problems regardingthedifferentmethods. 1.2. Faultdiagnosistasks According to the definitions available in the related literature, model-based FDI can be defined as the detection, isolation and identification of faults in a system by using methods that can extract features from measured signals and use a priori information on the process available in terms of mathematical models. Faults are, thus, detected by setting fixed or variable thresholds on residual signals generated from the difference between actual measurements and their estimates obtained by usingtheprocessmodel. Anumberofresidualscanbedesigned,witheachhavingsensitivitytoindividual faults occurring in different locations of the system. The analysis of each residual, oncethethresholdisexceeded,thenleadstofaultisolation. Figure 1.1 shows the general model-based FDI system. It comprises two main stages of residual generation and residual evaluation. This structure was first suggested in Chow and Willsky (1980) and now is widely accepted by the fault diagnosiscommunity.