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Systems modeling and computer simulation
Book Reviews studies of actual system designs from the author's industnal experience. Starting with specifications, how does one size the components, check the performance by paper analysis and simulation, add compensation if needed, re-analyze, and finally converge on a specific design? Also, how is the prototype system laboratory tested to substantiate predicted performance? In fact, how does the behavior of the real hardware compare with the math model for any of the many devices and systems studied in the book? I could not find a single example where measured behavior is compared with that predicted. This is the kind of information industrial practitioners deal with daily and that academics could use to augment their more theoretical teaching. If considerations of industrial secrecy and competitive advantage are preventing the dissemination of such material, I would encourage those involved to re-think this short-sighted view. Several sections of the text devoted to valve analysis presented material which I found new and useful. The two-spool flow-control valve (I believe this was invented by the author) is particularly interesting. Again, however, there is no discussion making clear the status of this design relative to more conventional valves. Is it regularly used in many applications? A design case study showing why such a valve was actually chosen in preference ~to another would be illuminating.
823
in summary, this book has a lot of useful information in it, but most of it has been available elsewhere for some time, in more accessible form.
References Andersen, B. W. (1967). The Analysis and Design of Pneumatic Systems. Wiley, New York. Merritt, H. E. (1967). Hydraulic Control Systems. Wiley, New York.
About the reviewer Professor Doebelin holds a B.Sc. from Case Institute of Technology and M.Sc. and Ph.D degrees from The Ohio State University, all in mechanical engineering. He has taught at the Ohio State Mechanical Engineering Department from 1954 to the present, using summer terms to acquire industrial experience in the aircraft and automotive industries. His main focus has been on teaching, course/lab development, and textbook writing. He has originated, developed, and regularly teaches eight courses and seven associated laboratories (sophomore to Ph.D. level) in System Dynamics, Measurement, and Control and is the author of five books in these areas.
Systems Modeling and Computer Simulation* Naim A. Kheir
Reviewer: J. DASTYCH Ruhr University Bochum, Lehrstuhl Eiektrische Steuerung and Rcgelung, Postfach 102148, D-4630 Bochum 1, F.R.G THE nOOK Systems Modeling and Computer Simulation is partly concerned with the fundamentals of control systems and systems theory, such as the introduction to continuous time and discrete time systems. It is based on the concept of deepening t h e outlook on basic mathematics, control engineering and some further ideas derived thereof by means of solved problems. This is initially carried out for some electrical and mechanical systems and leads to the statement of problems and their solutions on a more generalized level. These preliminary chapters are enhanced by some fundamentals of discrete time systems. Some common methods basic to control systems theory, e.g. the Routh-Hurwitz and root locus methods, as well as some system properties such as controllability and observability, are introduced. Chapter 3 bridges the gap in computer simulation methods and applications. An approach to discrete event system simulation is made, while the underlying statistical models are gone into in a comprehensible manner; e.g. the stating of different types of probability distributions is enhanced by a queueing model. As is often done, the simulation of dynamic systems is introduced via numerical integration based on Euler's method and continues with an introduction to error evaluation. Here, as is the case in almost every chapter, there is a brief outlook of software products on the market. Standard methods of analogue computer simulation, e.g. magnitude scaling, time scaling, and analogue programming are also dealt with. In the final chapter of this part, some further practical aspects concerning the design and the analysis of applied computer simulation problems is made.
* Systems Modeling and Computer Simulation by Naim A. Kheir. Marcel Dekker, N.Y. (1988). ISBN 0-82-47-7812X. $119.50.
As this book is obviously designed to provide a conclusive introduction in the fields of modeling and computer simulation, some aspects of large scale systems must be catered for as well. In this context, the idea of aggregation is developed for linear systems in the state-space representation. However, this approach is a rather condensed one, which is merely tailored to the needs of the reader who has acquired a degree Of proficiency in systems theory. At this stage, some aspects of the synthesis of regulators are introduced, and are extended in the more advanced chapters. The discussion of problems and their solution by means of existing CAD programs is of interest. The entire first part of the book should be considered as an introduction to the fundamentals of systems theory, control systems engineering and computer simulation. Even though the reader is encouraged by extensive examples and problems to further pursue his studies in the subject, he may still have to take recourse to the stated sources. In particular, this applied to the "Introduction to Large Scale Systems". In the second part of the book, effort is made to provide the appropriate tools for solving the problems from the first part. A general introduction to data structures and programming languages, which is unbiased to spedfic languages, includes a comparison of a few standard programming languages and some designed for computer simulation. In this context, the C programming language is omitted altogether. The description of operating systems is based on some fundamentals of computer architecture, with some interface techniques, e.g. A / D and D / A conversion are dealt with. Problems of analogue and digital computer simulation are treated repeatedly. The characteristic robot arm model simulation is explained by example with a program for the 2920 processor in assembler language. With regard to the third part of the book titled "Application", it is of interest that the fundamentals of discretizing continuous systems are treated again and hence some state of the art methods for the synthesis of SISO control systems and observers as well as the design of robust
824
Book Reviews
control systems are derived. This section is extended by some ideas basic to the modeling of robot arm physics. Various description of co-ordinate transforms and basics are given in a clear fashion. When it comes to a comprehensive survey with regard to the applications of computer simulation methods, the discussion of the so-called world models is a must. This book is no exception to this rule. However, there is neither a critical approach to the multitude of different world models nor to the outcome of their simulation. Of the pages on object-orientated simulation, 30 are dedicated to the computer simulation system SIMAN and are thus really an introduction to this software product, The third part of this book is concluded by a short chapter on multiprocessor systems. The appendix to this book, which is on computer-aided control systems, can be highly recommended, for this chapter is an adequate introduction to the wide range of CAD tools.
It comes with a table of CACSD programs and their distinctive features. As a whole, this bulky book (706 pages) can be of assistance for evaluating and applying means and methods for system modeling and computer simulation. Since there are problems and solutions in each chapter it wilt be of potential use in the training of professionals in the fields of technical engineering, control systems engineering, and computer simulation. About the reviewer
Dr.-lng. J. Dastych is a scientific research assistant and senior lecturer at the Department of Electrical Engineering at Ruhr Universitiit Bochum, Germany. He studied electrical engineering and in 1983 submitted his doctoral dissertation in control systems engineering. His present research activities have focussed on computer simulation methods, CAD systems for application in control systems engineering, and robust control.
Feedback Control Systems* Charles
L. P h i l l i p s a n d R o y c e
Reviewer: J. C. WEST
University of Bradford, W. Yorkshire, United Kingdom. IT WAS the real achievements in engineering during the last war that caused "control" to come to prominence and be regarded as of importance in the education of professional engineers. The first textbooks appeared in the late 1940s and well over a thousand works in the English language have appeared since then dedicated to undergraduate and senior level students. The changes in four decades have been enormous, not only in range, level and content of the material, but also in the attitude and competence of the readers. It is hard to remember that digital computing played no part in World War II and that control developed from infancy to maturity without the benefit of solid state electronics or digital computing. Control of physical entities whether blood temperature or steel plate thickness is fundamentally an analogue phenomenon. Student-led demand in the 1960s created B.Sc. or B.Eng. courses specialising in control; attendance has now reduced as student numbers have fallen by a factor of ten. On the other hand, the requirement for control as part of the core material for professional engineers in all branches continues to grow. Today's student is well equipped for all aspects of work in system dynamics and operational techniques. This makes the introduction of control that much easier. There has been so much development in both theory and range of application that the problem for the educator is to be able to define the boundaries and to gauge the conceptual level and abilities of the students. When a new textbook appears one has to question: What does it cover? What does it leave out? How adequate is the coverage? What is the experience of the authors? Is there anything new, not in other books? Does it bring anything novel in the educational sense? Finally, considering the esoteric levels of some works on control theory, one has to be concerned with the mathematical side. The authors Phillips and Harbor, as well as being responsible for the regular university courses, have had considerable experience designing and running intensive short courses for practising engineers on both sides of the Atlantic. The attitudes and demands of these participants * Feedback Control Systems by Charles L. Phillips and Royce D. Harbor. Prentice-Hall International, U.K. (1988). ISBN 13-313891-7. £15.95 U.S. $27.95.
D.
Harbor
have greatly influenced the teaching approach. Throughout the book great care is taken to differentiate between analysis and design. The practical side of design is particularly well-emphasised. Over-simplifying, the thesis is that analysis determines the characteristics of a given system and that design based on the analytical experience is about creating a system of pre-specified characteristics. The book is primarily aimed at self-education but a consequence is that it gives abundant material for lecturers, tutors and for class working. Each chapter contains many examples of both analysis and design, fully worked out and in order of difficulty. Each also finishes with a summary of what the student should have grasped, at a level of crispness which will make the reader check his own accomplishment. The chapters also include references for further work and a set of examples to tackle. The preface also informs us of a computer software package based on the set problems. The object of these computer programmes is to allow analysis and design using simulation by both classical and modern methods. This must be a bonus for the self learner. Just over a half of the book is concerned with linear analogue control systems leading up to stability analysis by Hurwitz-Routh, and Bode and Nyquist with coverage of sensitivity, disturbance rejection, accuracy and closed loop frequency response. A whole chapter is devoted to frequency response design but the major contribution is the large section on root-locus design and practical limitations. Many undergraduate courses do not go any further but the present demand is such that this book extends considerably into Digital Control and Sampled Data Systems, including design. Chapter 13 is entitled Modern Control Design; this turns out to be the integration of all the frequency response root-locus techniques and state variable techniques dealt with in the preceding parts. The chapter culminates with a unified design procedure based on pole-placement and some state variable estimation. It is a very useful and masterful account. One single final chapter tries to deal with the whole of the non-linear problem. It introduces the extension of Nyquist via the describing function but does not include the dual-input describing function, so much in demand in designing robotic systems. It introduces the phase plane and talks about limit cycles and Lyapunov Stability. It is a very elementary and basic approach and is not in keeping with the rest of the work which is of a high teaching merit. Nowhere in the text is the concept of a real signal, i.e. a continuously varying random process introduced. This would have enhanced the range and enabled the reader simply to
823
in summary, this book has a lot of useful information in it, but most of it has been available elsewhere for some time, in more accessible form.
References Andersen, B. W. (1967). The Analysis and Design of Pneumatic Systems. Wiley, New York. Merritt, H. E. (1967). Hydraulic Control Systems. Wiley, New York.
About the reviewer Professor Doebelin holds a B.Sc. from Case Institute of Technology and M.Sc. and Ph.D degrees from The Ohio State University, all in mechanical engineering. He has taught at the Ohio State Mechanical Engineering Department from 1954 to the present, using summer terms to acquire industrial experience in the aircraft and automotive industries. His main focus has been on teaching, course/lab development, and textbook writing. He has originated, developed, and regularly teaches eight courses and seven associated laboratories (sophomore to Ph.D. level) in System Dynamics, Measurement, and Control and is the author of five books in these areas.
Systems Modeling and Computer Simulation* Naim A. Kheir
Reviewer: J. DASTYCH Ruhr University Bochum, Lehrstuhl Eiektrische Steuerung and Rcgelung, Postfach 102148, D-4630 Bochum 1, F.R.G THE nOOK Systems Modeling and Computer Simulation is partly concerned with the fundamentals of control systems and systems theory, such as the introduction to continuous time and discrete time systems. It is based on the concept of deepening t h e outlook on basic mathematics, control engineering and some further ideas derived thereof by means of solved problems. This is initially carried out for some electrical and mechanical systems and leads to the statement of problems and their solutions on a more generalized level. These preliminary chapters are enhanced by some fundamentals of discrete time systems. Some common methods basic to control systems theory, e.g. the Routh-Hurwitz and root locus methods, as well as some system properties such as controllability and observability, are introduced. Chapter 3 bridges the gap in computer simulation methods and applications. An approach to discrete event system simulation is made, while the underlying statistical models are gone into in a comprehensible manner; e.g. the stating of different types of probability distributions is enhanced by a queueing model. As is often done, the simulation of dynamic systems is introduced via numerical integration based on Euler's method and continues with an introduction to error evaluation. Here, as is the case in almost every chapter, there is a brief outlook of software products on the market. Standard methods of analogue computer simulation, e.g. magnitude scaling, time scaling, and analogue programming are also dealt with. In the final chapter of this part, some further practical aspects concerning the design and the analysis of applied computer simulation problems is made.
* Systems Modeling and Computer Simulation by Naim A. Kheir. Marcel Dekker, N.Y. (1988). ISBN 0-82-47-7812X. $119.50.
As this book is obviously designed to provide a conclusive introduction in the fields of modeling and computer simulation, some aspects of large scale systems must be catered for as well. In this context, the idea of aggregation is developed for linear systems in the state-space representation. However, this approach is a rather condensed one, which is merely tailored to the needs of the reader who has acquired a degree Of proficiency in systems theory. At this stage, some aspects of the synthesis of regulators are introduced, and are extended in the more advanced chapters. The discussion of problems and their solution by means of existing CAD programs is of interest. The entire first part of the book should be considered as an introduction to the fundamentals of systems theory, control systems engineering and computer simulation. Even though the reader is encouraged by extensive examples and problems to further pursue his studies in the subject, he may still have to take recourse to the stated sources. In particular, this applied to the "Introduction to Large Scale Systems". In the second part of the book, effort is made to provide the appropriate tools for solving the problems from the first part. A general introduction to data structures and programming languages, which is unbiased to spedfic languages, includes a comparison of a few standard programming languages and some designed for computer simulation. In this context, the C programming language is omitted altogether. The description of operating systems is based on some fundamentals of computer architecture, with some interface techniques, e.g. A / D and D / A conversion are dealt with. Problems of analogue and digital computer simulation are treated repeatedly. The characteristic robot arm model simulation is explained by example with a program for the 2920 processor in assembler language. With regard to the third part of the book titled "Application", it is of interest that the fundamentals of discretizing continuous systems are treated again and hence some state of the art methods for the synthesis of SISO control systems and observers as well as the design of robust
824
Book Reviews
control systems are derived. This section is extended by some ideas basic to the modeling of robot arm physics. Various description of co-ordinate transforms and basics are given in a clear fashion. When it comes to a comprehensive survey with regard to the applications of computer simulation methods, the discussion of the so-called world models is a must. This book is no exception to this rule. However, there is neither a critical approach to the multitude of different world models nor to the outcome of their simulation. Of the pages on object-orientated simulation, 30 are dedicated to the computer simulation system SIMAN and are thus really an introduction to this software product, The third part of this book is concluded by a short chapter on multiprocessor systems. The appendix to this book, which is on computer-aided control systems, can be highly recommended, for this chapter is an adequate introduction to the wide range of CAD tools.
It comes with a table of CACSD programs and their distinctive features. As a whole, this bulky book (706 pages) can be of assistance for evaluating and applying means and methods for system modeling and computer simulation. Since there are problems and solutions in each chapter it wilt be of potential use in the training of professionals in the fields of technical engineering, control systems engineering, and computer simulation. About the reviewer
Dr.-lng. J. Dastych is a scientific research assistant and senior lecturer at the Department of Electrical Engineering at Ruhr Universitiit Bochum, Germany. He studied electrical engineering and in 1983 submitted his doctoral dissertation in control systems engineering. His present research activities have focussed on computer simulation methods, CAD systems for application in control systems engineering, and robust control.
Feedback Control Systems* Charles
L. P h i l l i p s a n d R o y c e
Reviewer: J. C. WEST
University of Bradford, W. Yorkshire, United Kingdom. IT WAS the real achievements in engineering during the last war that caused "control" to come to prominence and be regarded as of importance in the education of professional engineers. The first textbooks appeared in the late 1940s and well over a thousand works in the English language have appeared since then dedicated to undergraduate and senior level students. The changes in four decades have been enormous, not only in range, level and content of the material, but also in the attitude and competence of the readers. It is hard to remember that digital computing played no part in World War II and that control developed from infancy to maturity without the benefit of solid state electronics or digital computing. Control of physical entities whether blood temperature or steel plate thickness is fundamentally an analogue phenomenon. Student-led demand in the 1960s created B.Sc. or B.Eng. courses specialising in control; attendance has now reduced as student numbers have fallen by a factor of ten. On the other hand, the requirement for control as part of the core material for professional engineers in all branches continues to grow. Today's student is well equipped for all aspects of work in system dynamics and operational techniques. This makes the introduction of control that much easier. There has been so much development in both theory and range of application that the problem for the educator is to be able to define the boundaries and to gauge the conceptual level and abilities of the students. When a new textbook appears one has to question: What does it cover? What does it leave out? How adequate is the coverage? What is the experience of the authors? Is there anything new, not in other books? Does it bring anything novel in the educational sense? Finally, considering the esoteric levels of some works on control theory, one has to be concerned with the mathematical side. The authors Phillips and Harbor, as well as being responsible for the regular university courses, have had considerable experience designing and running intensive short courses for practising engineers on both sides of the Atlantic. The attitudes and demands of these participants * Feedback Control Systems by Charles L. Phillips and Royce D. Harbor. Prentice-Hall International, U.K. (1988). ISBN 13-313891-7. £15.95 U.S. $27.95.
D.
Harbor
have greatly influenced the teaching approach. Throughout the book great care is taken to differentiate between analysis and design. The practical side of design is particularly well-emphasised. Over-simplifying, the thesis is that analysis determines the characteristics of a given system and that design based on the analytical experience is about creating a system of pre-specified characteristics. The book is primarily aimed at self-education but a consequence is that it gives abundant material for lecturers, tutors and for class working. Each chapter contains many examples of both analysis and design, fully worked out and in order of difficulty. Each also finishes with a summary of what the student should have grasped, at a level of crispness which will make the reader check his own accomplishment. The chapters also include references for further work and a set of examples to tackle. The preface also informs us of a computer software package based on the set problems. The object of these computer programmes is to allow analysis and design using simulation by both classical and modern methods. This must be a bonus for the self learner. Just over a half of the book is concerned with linear analogue control systems leading up to stability analysis by Hurwitz-Routh, and Bode and Nyquist with coverage of sensitivity, disturbance rejection, accuracy and closed loop frequency response. A whole chapter is devoted to frequency response design but the major contribution is the large section on root-locus design and practical limitations. Many undergraduate courses do not go any further but the present demand is such that this book extends considerably into Digital Control and Sampled Data Systems, including design. Chapter 13 is entitled Modern Control Design; this turns out to be the integration of all the frequency response root-locus techniques and state variable techniques dealt with in the preceding parts. The chapter culminates with a unified design procedure based on pole-placement and some state variable estimation. It is a very useful and masterful account. One single final chapter tries to deal with the whole of the non-linear problem. It introduces the extension of Nyquist via the describing function but does not include the dual-input describing function, so much in demand in designing robotic systems. It introduces the phase plane and talks about limit cycles and Lyapunov Stability. It is a very elementary and basic approach and is not in keeping with the rest of the work which is of a high teaching merit. Nowhere in the text is the concept of a real signal, i.e. a continuously varying random process introduced. This would have enhanced the range and enabled the reader simply to