Control and the digital computer: the early years (original) (raw)
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Modern Control Theory -A historical perspective
val, 2019
The purpose of this paper is to present a brief sketch of the evolution of modern control theory. Systems theory witnessed different stages and approaches, which will be very shortly presented. The main idea is that, at present, Control Theory is an interdisciplinary area of research where many mathematical concepts and methods work together to produce an impressive body of important applied mathematics. A general conclusion is that the main advances in Control of Systems would come both from mathematical progress and from technological development. We start with frequency-domain approach and end our historical perspective with structural-digraph approach, passing through time-domain, polynomial-matrix-domain frequential and geometric approaches.
A brief history of automatic control
IEEE Control Systems Magazine
utomatic feedback control systems have been known and used for more than 2000 years; some of the earliest examples are water clocks described by Vitruvius and attributed to Ktesi bios (circa 270 B.C.). Some three hundred years later, Heron of Alexandria described a range of automata which employed a variety of feedback mechanisms. The word "feedback" is a 20th century neologism introduced in the 1920s by radio engineers to describe parasitic, positive feeding back of the signal from the output of an amplifier to the input circuit. It has entered into common usage in the English-speaking world during the latter half of the century. Automatic feedback is found in a wide range of systems; Rufus Oldenburger, in 1978, when recalling the foundation of IFAC, commented on both the name and the breadth of the subject: "I felt that the expression 'automatic control' covered all systems, because all systems involve variables, and one is concerned with keeping these variables at constant or given varying values. This amounts to conccrn about control of these variables even though no actual automatic control devices may be intentionally or otherwise incorporated in these systems. I was thinking of biological, economic, political as we\1 as engineering systems so that I pictured the scope ofIFAC as a very broad one." This divcrsity poses difficultics for historians of the subject (and for editors of control journals), and this article does not attempt to cover all application areas. Thc history of automatic control divides conveniently into four main periods as follows:
MATLAB® and Simulink® are a trademark of The MathWorks, Inc. and is used with permission. The MathWorks does not warrant the accuracy of the text or exercises in this book. This book's use or discussion of MATLAB® and Simulink® software or related products does not constitute endorsement or sponsorship by The MathWorks of a particular pedagogical approach or particular use of the MATLAB® and Simulink® software.
2007
This paper presents a survey of the early development of automation technology and control science in Italy. The main focus is on the crucial period from 1950 through 1970. Some attention, though, has been paid also to more ancient significant events, from the Middle Ages to the first half of the XXth century. Equally included are some hints to events that occurred in the decades following 1970. However, these more recent scientific achievements are better understood within the frame of the main international stream rather than in any local perspective. As such, they have been somewhat overlooked in the present survey.
Computer Controlled Systems Astrom 3rdEd
Background Material A broad outline of compu ter-controlled systems is presented in the first chapter. This gives a historical perspective on the development ofcomputers. control systems, and relevant theory. Some key points of the theoryand the behavior ofcomputer-control systems are also given, together with many examples. Analysis and Design ofDiscrete-Time Systems It is possible to makedrastic simplifications in analysis and design by considering only the behavior ofthe system at the sampling instants. We call this the computer-oriented view. It is the view of the systemobtained by observing its behavior through the numbers in the computer. The reason for the simplicity is that the system can be described by linear difference equations with constant coefficients. This approach is covered in Chapters 2, 3.4 and 5. Chapter 2 describes how the discrets-time systems are obtained by sampling continuous-time systems. Both state-space models and input-output models are given. Basic properties of the models are also given together with mathematicaltools such as the a-transform. Tools for analysis are presented in Chapter 3. Chapter 4 deals with the traditional problem of state feedback and observers, but it goes much further than what is normally covered. in similar textbooks. In particular, the chapter shows how to deal with load disturbances, feedforward, and command-signal following. Taken together, these features give the controller a structure that can cope with many of the cases typically found in applications. An educational advantage is that students are equipped with tools to deal with real design issues after a very short time. Chapter 5 deals with the problems of Chapter 4 from the input-output point of view, thereby giving an alternative view on the design problem. All issues discussed in Chapter 4 are also treated in Chapter 5. This affords an excellent way to ensure a good understanding of similarities and differences between stete-space and polynomial approaches. The polynomial approach also makes it possible to deal with the problems of modeling errors and robustness, which cannot he conveniently handled by state-space techniques. Having dealt with specific design methods, we present general aspects of the design of control systems in Chapter 6. This covers structuring of large systems as well as bottom-up and top-down techniques. Broadening the View Although many issues in computer-controlled systems can be dealt with using the computer-oriented view, there are some questions that require a detailed study of the behavior of the system between the sampling instants. Suchproblems arise naturally ifa computer-controlled system is investigated through the analog signalsthat appear in the process. We call this the process-oriented view. It typically leads to linear systems with periodic coefficients. This gives rise to phenomena such as aliasing, which may lead to very undesirable effects unless special precautions are taken. It is veryimportant to understand both this and the design of anti-aliasing filters when investigating computer-controlled. systems. Tools for this are developed in Chapter 7. Preface Ix When upgrading older control equipment, sometimes analog designs of controllers may be available already. In such cases it may be cost effective to have methods to translate analog designs to digital control directly. Methods for this are given in Chapter 8. Implementation It is not enough to know about methods of analysis and design. A control engineer should also be aware of implementation issues. These are treated in Chapter g, which covers matters such as prefiltering and computational delays, numerics, programming, and operational aspects. At this stage the reader is well prepared for all steps in design, from concepts to computer implementation. More Advanced Design Methods To make more effective designs of control systems it is necessary to better characterize disturbances. This is done in Chapter 10. Having such descriptions it is then possihle to design for optimal performance. This is done using state-space methods in Chapter 11and by using polynomial techniques in Chapter 12. So far it has been assumed that models ofthe processes and their disturbances are available. Experimental methods to obtain such models are described in Chapter 13. Prerequisites The book is intended for a final-year undergraduate or a first-year graduate course for engineering majors. It is assumed that the reader has had an introductory course in automatic control. The book should be useful for an industrial audience. Course Configurations The book has been organized 80 that it can be used in different ways. An introductory course in computer-controlled systems could cover Chapters 1, Ｒ ｾ 3, 4, 5, and 9. A more advanced course might include all chapters in the book A course for an industrial audience could contain Chapters 1, parts of Chapters 2,3,4, and 5, and Chapters 6, 7,8, and 9. 'Ib get the full henefit of a course, it is important to supplement lectures with problem-solving sessions, simulation exercises, and laboratory experiments. Computetional Tools Computer tools for analysis, design, and simulation are indispensable tools when working with computer-controlled systems. The methods for analysis and design presented in this book can be performed very conveniently using M.\r-LAB®. Many of the exercises also cover this. Simulation ofthe system can similarly be done with Simnon® or SIMULINX®. There are 30 figures that illustrate various aspects of analysis and design that have been performed using MATLAB®, and 73 fignres from simulations using SrMULTNK®. Macros and mfiles are available from anonymous FrP from ftp. control. 1th. se, directory Ipub/bookslecs. Other tools such as Simnon® and Xmath® can be used also. x Preface Supplements Complete solutions are available from the publisher for instructors who have adopted our book. Simulation macros, transparencies, and examples ofexaminations are available on the World Wide Web at http://ww.control.lth.se; see Education/Computer-Controlled Systems.
Computer Controlled Systems Astrom 3rdEdition
JE if\': 49.00 JG Preface A consequence of the revolutionary advances in microelectronics is that prac-, tically all control systems constructed today are based on microprocessors and sophisticated microcontrollers. By using computer-controlled systems it is possible to obtain higher performance than with analog systems, as well as new functionality. New software tools havealsodrastically improved the engineering efficiency in analysis and design of control systems.