Table Of ContentControl of Complex Systems
Karl Astrom, Pedro Albertos,
Mogens Blanke, Alberto Isidori,
Walter Schaufelberger and Ricardo Sanz (Eds.)
Control of Complex
Systems
With 142 Figures
Springer
Karl Âstrom, MSe, PhD
Department of Automatic Control, Lund Institute of Teehnology, Box 118,
221 00 Lund, Sweden
Pedro Albertos, PhD
Departamento de Ingenierfa de Sistemas y Automâtica, Universidad
Politeenica de Valencia, Apdo.22012, E-46071 Valencia, Spain
Mogens Blanke, MSe EE, PhD
Department of Control Engineering, Aalborg University, 9220 Aalborg, Denmark
Alberto Isidori, Professor
Dipartimento de Informatica e Sistemistica, Universita de Roma (La Sapienza),
Via Eudossiana 18,00184 Rome, Italy
Walter Sehaufelberger, Dr.Se. Teehn
Institut fur Automatik, ETH-Z/ETL 8092 Zurich, Switzerland
Ricardo Sanz, PhD
Departamento de Automâtica, Universidad Politeenica de Madrid,
e Iose Gutierrez Abaseal2, E-28006 Madrid, Spain
ISBN 978-1-4471-1074-3
British Library Cataloguing in Publication Data
Control of complex systems
l.Automatic contro12.Control theory
I.Astrom, Karl J. (Karl Johan), 1934-
629.8'312
ISBN 978-1-4471-1074-3 ISBN 978-1-4471-0349-3 (eBook)
DOI 10.1007/978-1-4471-0349-3
Library of Congress Cataloging-in-Publication Data
A catalog record for this book is availab1e from the Library of Congress
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 repro
duced, 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 of licences
issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms
should be sent to the publishers.
© Springer-Verlag London 2001
Originally published by Springer-Verlag London Limited in 2001
Softcover reprint of the hardcover 1s t edition 2001
The use of registered names, trademarks etc. in this publication does not imply, even in the absence
of a specific statement, that such names are exempt from the relevant laws and regulations and there
fore free for general use.
The publisher makes no representation, express or implied, with regard to the accuracy of the infor
mation contained in this book and cannot accept any legal responsibility or liability for any errors
or omissions that may be made.
Typesetting: Camera ready by contributors
69/3830-543210 Printed on acid-free paper SPIN 10767832
Complexity
is in the eye of the beholder
Preface
The world of artificial systems is reaching complexity levels that es
cape human understanding. Surface traffic, electricity distribution, air
planes, mobile communications, etc., are examples that demonstrate that
we are running into problems that are beyond classical scientific or engi
neering knowledge.
There is an ongoing world-wide effort to understand these systems and
develop models that can capture its behavior. The reason for this work is
clear, if our lack of understanding deepens, we will lose our capability to
control these systems and make they behave as we want.
Researchers from many different fields are trying to understand and
develop theories for complex man-made systems. This book presents re
search from the perspective of control and systems theory.
The book has grown out of activities in the research program Control
of Complex Systems (COSY). The program has been sponsored by the Eu
ropean Science Foundation (ESF) which for 25 years has been one of the
leading players in stimulating scientific research. ESF is a European asso
ciation of more than 60 leading national science agencies spanning more
than 20 countries. ESF covers has standing committees in Medical Sci
ences, Life and Environmental Sciences, Physical and Engineering Sci
ences, Humanities and Social Sciences. The COSY program was ESF's
first activity in the Engineering Sciences. The program run for a period
of five years starting January 1995. It supported by ESF member Or
ganisations in Belgium, Denmark, Finland, Germany, Hungary, Italy, the
Netherlands, Poland, Portugal, Spain, Sweden, Switzerland, Turkey and
the United Kingdom.
The goal of the program was to promote a multi-disciplinary activ
ity, which will lead to a deeper understanding and development of con
trol technology for complex system and if possible to develop a basis for
a theory for them. The Programme was initially organised in four theme
groups: control of non-linear and uncertain systems, fault-tolerant control
systems, learning control systems and integration of complex control sys
tems. In the second phase of the COSY Programme, strong efforts were
made to increase interaction between the theme groups.
viii Preface
The program provided support for yearly meetings of the different
groups, an annual workshop and exchange of researchers. The research
itself was not supported by the program. The long range nature ofthe pro
gram made it possible to form research groups in different problem areas.
A problem may arise at a theme group meeting, as interest grew it was
possible to add researchers with complementary talent, discussions at the
annual workshop provided additional views and further work was carried
out by exchange of researchers. This type of activity was most noticeable
in the work on fault-tolerant systems and in integration of complex sys
tems.
The material in this book represents some of the results of the COSY
program. It should also be mentioned that there was much more work
done that for various reasons do not appear in the book. The book is orga
nized as a collection of essays, many of them are written by multiple au
thors. There are chapters on surveys of essential areas, discussion of spe
cific problems, case studies and benchmark problems. Complex systems
appear in many different fields and it is a research area that is receiving
much interest. Our work has made it clear that there are many highly
interesting research problems related to the complex engineering systems
that we are all benefitting from. Since these systems are man made they
may be easier to deal with than many other complex systems because
they are accessible for observation, experimentation and even, redesign.
Our work has clearly shown that complex engineering systems is indeed a
fruitful multi-disciplinary research field and that a good understanding of
the control technology for them it rests on three pillars, systems modeling,
communication and computing.
We would like to express our gratitude to ESF for providing support
for the work and we would also like to thank Dr. Hans Karov the program
director ofthe ESF Committee for Physical and Engineering Sciences who
provided very good guidance. We would also like to thank all the partici
pants of the program for their efforts.
MANFRED THOMA
KARL J OHAN ASTROM
Contents
1. Introduction.............................................. 1
1.1 Complex Systems and Control. . . . . . . . . . . . . . . . . . . . . . . . .. . 1
1.2 Complex Engineering Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 The Role of Feedback ................................... 10
1.4 Dynamics and Control .................................. 13
1.5 The Nature of Failures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 17
1.6 Research Challenges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 18
1.7 About the Book. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 19
2. Modeling Complex Physical Systems ...................... 21
2.1 Introduction........................................... 21
2.2 The Modelica Project. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 22
2.3 Composition Diagrams .................................. 23
2.4 Modelica Details. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 27
2.5 Non-causal Modeling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 30
2.6 Advanced Modeling Features . . . . . . . . . . . . . . . . . . . . . . . . . . .. 32
2.7 Standard Libraries ..................................... 35
2.8 Future Development. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 36
2.9 Conclusions............................................ 37
3. Passivity-based Control of Non-linear Systems. . . . . . . . . . .. 39
3.1 Introduction........................................... 39
3.2 Passivity and Stability Analysis of Feedback Interconnec-
tions .................................................. 42
3.3 Feedback Passivity and Stabilization. . . . . . . . . . . . . . . . . . . .. 49
3.4 Euler-Lagrange Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 57
3.5 Disturbance Attenuation and Hoo Control ................ 65
4. An Introduction to Forwarding . . . . . . . . . . . . . . . . . . . . . . . . . .. 77
4.1 Introduction........................................... 77
4.2 C1 Dissipative Systems ................................. 78
4.3 C1 Dissipative Systems via Reduction or Extension. . . . . . .. 82
4.4 Exact Change of Coordinates .. . . . . . . . . . . . . . . . . . . . . . . . . .. 86
4.5 Approximate Change of Coordinates ..................... 95
x Contents
5. Iterative Identification and Control Design. . . . . . . . . . . . . .. 101
5.1 Introduction ........................................... 101
5.2 Youla Parametrization .................................. 102
5.3 A Generic Two-degree of Freedom Controller .............. 106
5.4 Optimization of the Generic Scheme ...................... 109
5.5 A New Closed-loop System Parametrization ............... 111
5.6 Asymptotic Variances for K-B-Parametrization ............ 113
5.7 Iterative Controller Refinement .......................... 114
5.8 Robustness and Sensitivity .............................. 116
5.9 Product Inequalities .................................... 119
6. Learning Control of Complex Systems . . . . . . . . . . . . . . . . . . .. 123
6.1 Introduction ........................................... 123
6.2 Model Structures for Learning .......................... , 126
6.3 Control Structures for Learning .......................... 128
6.4 Learning Paradigms .................................... 130
6.5 A General Framework for On-line Learning ............... 135
6.6 Validation ............................................. 139
6.7 Conclusions ............................................ 141
7. Software for Complex Controllers ........................ 143
7.1 Introduction ........................................... 143
7.2 An Evolving Paradigm ......... , ........................ 146
7.3 Emerging Software Concepts ............................ 148
7.4 On to Standardization .................................. 154
7.5 Sample Complex Software Controllers .................... 159
7.6 The Future of Software for Control ...................... , 163
8. Fault-tolerant Control Systems ........................... 165
8.1 Introduction ........................................... 165
8.2 Basic Definitions ....................................... 167
8.3 Analysis of Fault Propagation ........................... 171
8.4 Analysis of Structure ................................... 173
8.5 Recoverability .......................................... 176
8.6 Autonomous Fault-tolerant Control ...................... 181
8.7 An Example: Ship Propulsion ........................... 185
8.8 Summary .............................................. 188
9. Fault Detection and Isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 191
9.1 The Principle of Model-based Fault Diagnosis ............. 191
9.2 Signal-based FDI Approach ............................. 194
9.3 Quantitative Model-based FDI Approach ................. 196
9.4 Qualitative Model-based FDI Approach .................. 203
9.5 Summary .............................................. 207
Contents xi
10. Residual Generation for FDI in Non-linear Systems ...... 209
10.1 Introduction ........................................... 209
10.2 Algebraic Approach ..................................... 210
10.3 Geometric Approach .................................... 217
10.4 Conclusion ............................................. 226
11. Predictive Methods for FTC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 229
11.1 Introduction ........................................... 229
11.2 Predictive Control ...................................... 230
11.3 Embedding Fault Tolerance in Predictive Control .......... 234
11.4 Model Adaptation and Management ...................... 235
11.5 Modifying Control Objectives .......... " ................ 238
11.6 Current Industrial Practice .............................. 239
11.7 Conclusions ............................................ 240
12. Three-tank Control Reconfiguration ...................... 241
12.1 The Benchmark Problem ................................ 241
12.2 Reconfigurability Analysis ............................... 248
12.3 Reconfiguration Based on a Qualitative Model ............ 255
12.4 A Hybrid Approach to Reconfigurable Control ............. 262
12.5 A Multi-model-based Reconfigurable Control ............. 269
12.6 A Neural Observer-based Approach ...................... 275
12.7 Conclusions ............................................ 283
13. Ship Propulsion Control and Reconfiguration . . . . . . . . . . .. 285
13.1 Introduction ........................................... 285
13.2 Ship Propulsion System ................................. 286
13.3 Structural Analysis .................................... 295
13.4 Fault Detection: A Fuzzy Observer Approach ............. 299
13.5 Fault Detection: Non-linear Approach -1 ................. 302
13.6 Fault Detection: Non-linear Approach -2 ................. 305
13.7 Reconfiguration Using Software Redundancy ............. 307
13.8 Reconfiguration Using Predictive Control ................. 311
13.9 Summary and Conclusions .............................. 315
14. Learning Control of Thermal Systems .................... 317
14.1 Introduction ........................................... 317
14.2 On Thermal System Learning Control .................... 318
14.3 Controlling Kiln Heat Processing ........................ 320
14.4 Controlling Reheat Furnace Processes .................... 324
14.5 Hierarchical Control for Quality Ceramic Tiles ............ 330
14.6 Learning Control ofFBC Combustion .................... 332
14.7 Conclusions and Future Research ........................ 336
