BOOKSHELF
Interested in Reviewing? Readers interested in contributing reviews to the Bookshelf department should contact the associate editor for book reviews indicating their areas of expertise: Prof. Chris C. Bissell Department of Telematics The Open University Milton Keynes Great Britain MK7 6AA
[email protected]
Model Reduction for Control System Design, by G. Obinata and D.O. Anderson, Springer-Verlag, 2001, 168 pp., ISBN 1-85233-371-5, Euro 109.95. Reviewed by Paul Stewart, University of Sheffield, U.K. This text provides the theoretical foundations for model and controller reduction and is aimed at students and industrial R&D engineers. More specifically, it addresses practitioners who are applying advanced control theory to real and real-time systems. The central objective of this technique is to retain the dominant modes of the original system and discard the nondominant modes. The thematic development takes the reader from a dissemination of model reduction methods to model and controller reduction based on coprime factorizations via multiplicative approximation and low-order controller design. Balanced truncation, Hankel norm reduction, and weighted methods are also discussed. A separate section is devoted to model reduction for discrete-time systems, further enhancing its applicability to real system problems. The practicing engineer will find this volume extremely useful in understanding and applying the many existing software packages for model and controller reduction. Numerous examples are provided to illustrate the the-
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ory expounded in the text; however, as is typical with this type of textbook, it would be better if the theory were developed on and applied to more specific and concrete contemporary engineering problems. Two noticeable features of the book are its readability and overall balance between mathematics and text. This is all the more remarkable in that it is a direct translation from the original Japanese. The book makes an interesting read, irrespective of one’s intended applications or teaching. It is especially useful when getting one’s hands dirty solving a problem. The authors have managed to distill a number of ap-
proaches and techniques into a single volume, and thus have achieved both a readable and usable text. The technical level might be slightly high for an undergraduate text, but I would certainly recommend it for inclusion in a postgraduate course of study. This volume arrived for review at just the right time, as I needed to apply some of the techniques to a real-time simulation problem. I used various techniques described in the book to solve a model reduction problem for a real-time multiple-aircraft flight simulator. The logical development of IEEE Control Systems Magazine
ideas in the book, combined with a clarity of description, reasonable examples, and (as far as I could see) error -free mathematics, made the application relatively trouble free. I used the text to develop bespoke algorithms for MATLAB, successfully reducing the model and controller order, giving accurate steady-state and dynamic response. Under such circumstances, I would highly recommend this book to any practicing engineer with interests in this field. In conclusion, it is a well-written, well-argued, and lucid text. It rates highly in both theoretical and practical terms, but it would broaden its appeal if it included some applied rather than mathematical examples. This might also make it more useful as an undergraduate text. Control Systems with Actuator Saturation, by Tingshu Hu and Zongli Lin, Birkhauser, 2001, 392 pp., ISBN 0-8176-4219-6, $89.95. Reviewed by Jason McConnell. The authors have provided a unique text for all scientists and engineers interested in control systems with actuator saturation. The presence of saturation nonlinearities is widespread, witnessed in most, if not all, engineering systems. As opposed to the ad hoc method of dealing with the effects caused by saturation, this text tackles the theoretically challenging problem in a systematic way. The proposed strategy identifies the saturation at the beginning of the control design, enabling a control law to be derived to meet the performance and stability requirements in its presence. In addition to providing a short introduction to systems with saturation nonlinearities, chapter 1 describes the notation used throughout the text. Chapters 2 and 3 describe the null controllable region for continuous and discrete time systems. The results of chapters 4 and 5 identify a domain of attraction in an effort to stabilize the origin of linear systems with actuator saturation.
February 2003
