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Modern digital control systems
0005 1098/84 $3.1)0+ 0.00 Pergamon PressLtd. ;ll[ 1984InternationalFederationof AutomaticControl
Automatica, Vol.20, No. 2, pp. 263-266, 1984
Printed in Great Britain.
Book Renews
Modern Digital Control Systems* Raymond G. Jacqout Reviewer: GI~NTHER S C H M I D T
familiarity with basic control concepts, Laplace transform and sdomain-techniques will be necessary for the reader to master the material. The second part introduces the state variable representation of digital control systems, both for the continuous-time (plant) and discrete-time (digital filter, compensator) case. Basic concepts, such as controllability, observability and the connection between continuous- and discrete-time representation are emphasized. Standard design methods for total and partial state feedback are discussed and various types of discrete-time state estimators as well as their application in total state feedback designs are demonstrated. As a next step the LQ-optimal control problem is introduced, followed by a discussion of basic properties of the optimal control laws, efficient algorithms for calculation of the feedback gains, and features of suboptimal designs employing estimated state feedback. These chapters are kept on a mathematically moderate level; nevertheless some familiarity with linear algebra, basic matrix theory and optimal control concepts is required. Part three of the book goes in some way beyond the scope of an introductory text. It starts with a review of fundamental material from the theory of probability and considers the problem of linear difference systems driven by noise signals. This is followed by a discussion of state estimation in the presence of noise and t he discrete-time Kalman-Bucy filter. It concludes with an outline of results following from the solution of the LGQ-optimal control problem. This part of the book can only be considered preliminary. For a deeper understanding of the material, additional knowledge of probability theory and continuous-time stochastic control seems to be indispensable for the reader. Summarizing, I came to the following conclusions about the book: Apart from the earlier discussed drawbacks with respect to its rather general title, the main body of the book together with its various appendices may be considered a nicely written standard text introducing basic and more advanced theory of linear discrete-time control systems. Although no essentially new viewpoints of the subject are given, the presentation of the material is based on great teaching experiences of its author. The book has two major deficiencies. As mentioned before, certain basic topics and from a practical viewpoint important issue, like ripple, finite pulse width or multi-rate sampling are not adequately treated. Furthermore, hardly no attempt is made to work out the strong and useful relations that exist between the results developed via the z-transform and the state-space approach. There are a number of typesetting errors. For example, in Fig. 2.4, two of the time responses for real axes pole locations are mixed up or in equation (9.1.3) the right-hand side must read
Lehrstuhl und Laboratorium lor Steuerungsund Regelungstechnik, Technische Universit//t Mfinchen, F.R.G. SINCE the advent of microprocessors in the beginning of the 1970s digital control systems has become one of the most active fields in control engineering. Hundreds of papers on applications and theoretical aspects of digital controls have been published. The freedom of design given by software-based controllers has led to many new and exciting solutions for real-world control problems. Nevertheless, even the more recent textbooks in the area of digital control systems seem to take only minor notice of these developments. Most texts are still devoted to a theory of linear discrete-time or sampled data control systems only, thus following more or less the traditional tracks laid by the famous early books on the subject area. The control algorithms developed are linear and of the output feedback/compensator or the state feedback/state observer type. Usually the implementation of these algorithms seems to take place in a rather artiticial digital environment, characterized by a pair of converters and something called a digital computer. Software related aspects of digital controls such as a computer language, a real-time operating system, etc., are seldom treated. The wealth of available non-conventional algorithms such as nonlinear adaptive control laws or the powerful combination of feedback and logic/sequence c o n t r o l - - t o mention just a few--are rarely taken into consideration. Although entitled Modern Digital Control Systems, the book follows more the traditional path. It has been written as an introductory text for engineering students in their final college or first graduate year as well as for use of the practicing engineer. The material presented can be decomposed into three parts: Chapters l - 5 and 7, introducing into analysis and synthesis of linear discrete-time deterministic systems based on z-transform techniques; Chapters 6, 8 and 9, extending this discussion from the state-space point of view; and Chapters 10-12, giving an outline of linear discrete-time stochastic estimation and control problems. Each chapter is accompanied by a number of well-chosen example problems (mostly from the process control field) emphasizing main theoretical results and basic practical ideas. The book enters into the mathematics of open-loop discretetime systems via linear difference equations and by introducing the z-transform. The pronerties of discrete systems are explored both from a frequency and time domain viewpoint. Basic requirements for the design of sampled-data control systems as well as the design of finite settling time or PID control algorithms are treated in some detail. On the other hand important basic issues, such as stability of discrete-time systems or sampling rate selection are only slightly touched. The chapter on design of linear digital filters and compensators is restricted to well-known methods for the approximation of a given s- by a z-transfer function. An extra chapter is included to relate the difference equation approach preferred in the book to the more traditional impulse sampling method followed by a discussion of results following from the sampling theorem. The section on quantization and error effects helps in bridging the gap between the designed compensator and its implementation on a digital system. Although this part of the book is selfcontained, some
(X,m.~)- 2. Altogether the book is not too different in its contents and presentation from others published in the same area over the last years. It can be recommended as a base for a first course in the field of sampled-data control systems. About the reviewer
Dr Gfinther Schmidt received his Dipl.-Ing. in 1960, and Dr.Ing. degree in 1966, both from the Faculty of Electrical Engineering of the Technische Universit/it Darmstadt, Germany. In 1967 he performed post-doctoral research work at the Division of Engineering Mechanics, Standford University, Ca. After spending four years as head of the Flight Control Group of the Dornier Aerospace Company, Friedrichshafen, Germany, he became full professor at the Technische Universit/it M~nchen, Germany and director of the Automatic Control Laboratory. Dr Schmidt's current research interests lie in the areas of computer control, large-scale and complex engineering systems and robotics.
* Modern Digital Control Systems, by R. G. Jacqout. Published by Marcel Dekker, New York (1981). 366 pp., SFll0. The books which are reviewed in the IFAC-Journal Automatica are not necessarily endorsed by IFAC, the editors, or the publisher nor are the reviewers' opinions or comments about the books.
263
Automatica, Vol.20, No. 2, pp. 263-266, 1984
Printed in Great Britain.
Book Renews
Modern Digital Control Systems* Raymond G. Jacqout Reviewer: GI~NTHER S C H M I D T
familiarity with basic control concepts, Laplace transform and sdomain-techniques will be necessary for the reader to master the material. The second part introduces the state variable representation of digital control systems, both for the continuous-time (plant) and discrete-time (digital filter, compensator) case. Basic concepts, such as controllability, observability and the connection between continuous- and discrete-time representation are emphasized. Standard design methods for total and partial state feedback are discussed and various types of discrete-time state estimators as well as their application in total state feedback designs are demonstrated. As a next step the LQ-optimal control problem is introduced, followed by a discussion of basic properties of the optimal control laws, efficient algorithms for calculation of the feedback gains, and features of suboptimal designs employing estimated state feedback. These chapters are kept on a mathematically moderate level; nevertheless some familiarity with linear algebra, basic matrix theory and optimal control concepts is required. Part three of the book goes in some way beyond the scope of an introductory text. It starts with a review of fundamental material from the theory of probability and considers the problem of linear difference systems driven by noise signals. This is followed by a discussion of state estimation in the presence of noise and t he discrete-time Kalman-Bucy filter. It concludes with an outline of results following from the solution of the LGQ-optimal control problem. This part of the book can only be considered preliminary. For a deeper understanding of the material, additional knowledge of probability theory and continuous-time stochastic control seems to be indispensable for the reader. Summarizing, I came to the following conclusions about the book: Apart from the earlier discussed drawbacks with respect to its rather general title, the main body of the book together with its various appendices may be considered a nicely written standard text introducing basic and more advanced theory of linear discrete-time control systems. Although no essentially new viewpoints of the subject are given, the presentation of the material is based on great teaching experiences of its author. The book has two major deficiencies. As mentioned before, certain basic topics and from a practical viewpoint important issue, like ripple, finite pulse width or multi-rate sampling are not adequately treated. Furthermore, hardly no attempt is made to work out the strong and useful relations that exist between the results developed via the z-transform and the state-space approach. There are a number of typesetting errors. For example, in Fig. 2.4, two of the time responses for real axes pole locations are mixed up or in equation (9.1.3) the right-hand side must read
Lehrstuhl und Laboratorium lor Steuerungsund Regelungstechnik, Technische Universit//t Mfinchen, F.R.G. SINCE the advent of microprocessors in the beginning of the 1970s digital control systems has become one of the most active fields in control engineering. Hundreds of papers on applications and theoretical aspects of digital controls have been published. The freedom of design given by software-based controllers has led to many new and exciting solutions for real-world control problems. Nevertheless, even the more recent textbooks in the area of digital control systems seem to take only minor notice of these developments. Most texts are still devoted to a theory of linear discrete-time or sampled data control systems only, thus following more or less the traditional tracks laid by the famous early books on the subject area. The control algorithms developed are linear and of the output feedback/compensator or the state feedback/state observer type. Usually the implementation of these algorithms seems to take place in a rather artiticial digital environment, characterized by a pair of converters and something called a digital computer. Software related aspects of digital controls such as a computer language, a real-time operating system, etc., are seldom treated. The wealth of available non-conventional algorithms such as nonlinear adaptive control laws or the powerful combination of feedback and logic/sequence c o n t r o l - - t o mention just a few--are rarely taken into consideration. Although entitled Modern Digital Control Systems, the book follows more the traditional path. It has been written as an introductory text for engineering students in their final college or first graduate year as well as for use of the practicing engineer. The material presented can be decomposed into three parts: Chapters l - 5 and 7, introducing into analysis and synthesis of linear discrete-time deterministic systems based on z-transform techniques; Chapters 6, 8 and 9, extending this discussion from the state-space point of view; and Chapters 10-12, giving an outline of linear discrete-time stochastic estimation and control problems. Each chapter is accompanied by a number of well-chosen example problems (mostly from the process control field) emphasizing main theoretical results and basic practical ideas. The book enters into the mathematics of open-loop discretetime systems via linear difference equations and by introducing the z-transform. The pronerties of discrete systems are explored both from a frequency and time domain viewpoint. Basic requirements for the design of sampled-data control systems as well as the design of finite settling time or PID control algorithms are treated in some detail. On the other hand important basic issues, such as stability of discrete-time systems or sampling rate selection are only slightly touched. The chapter on design of linear digital filters and compensators is restricted to well-known methods for the approximation of a given s- by a z-transfer function. An extra chapter is included to relate the difference equation approach preferred in the book to the more traditional impulse sampling method followed by a discussion of results following from the sampling theorem. The section on quantization and error effects helps in bridging the gap between the designed compensator and its implementation on a digital system. Although this part of the book is selfcontained, some
(X,m.~)- 2. Altogether the book is not too different in its contents and presentation from others published in the same area over the last years. It can be recommended as a base for a first course in the field of sampled-data control systems. About the reviewer
Dr Gfinther Schmidt received his Dipl.-Ing. in 1960, and Dr.Ing. degree in 1966, both from the Faculty of Electrical Engineering of the Technische Universit/it Darmstadt, Germany. In 1967 he performed post-doctoral research work at the Division of Engineering Mechanics, Standford University, Ca. After spending four years as head of the Flight Control Group of the Dornier Aerospace Company, Friedrichshafen, Germany, he became full professor at the Technische Universit/it M~nchen, Germany and director of the Automatic Control Laboratory. Dr Schmidt's current research interests lie in the areas of computer control, large-scale and complex engineering systems and robotics.
* Modern Digital Control Systems, by R. G. Jacqout. Published by Marcel Dekker, New York (1981). 366 pp., SFll0. The books which are reviewed in the IFAC-Journal Automatica are not necessarily endorsed by IFAC, the editors, or the publisher nor are the reviewers' opinions or comments about the books.
263