Ex. PGS 1045
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`COMPUTER-CONTROLLED
`SYSTEMS
`Theory and Design
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`Ex. PGS 1045
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`Theory and Design
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`Karl J. Astrom
`Bjorn Wittenmark
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`Prentice-Hall, Inc., Englewood Cliffs, N.J. 07632
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`Ex. PGS 1045
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`Library of Congress Cataloging in Publication Data
`AsmoM, KARL J. (Karl Johan).
`(date)
`Computer controlled systems.
`
`Inciudes bibliographies and index.
`l. Automatic control-Data processing.
`I. Wittenmark, B.
`II. Title.
`TJ213.A78 1984
`629.8'95
`ISBN 0-13-164319-3
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`83-17643
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`Editorial/production supervision
`and interior design: Karen Skrable
`Manufacturing buyer: Anthony Caruso
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`©1984 by Prentice-Hall, Inc., Englewood Cliffs, N.J. 07632
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`All rights reserved. No part of this book
`may be reproduced in any form or
`by any means without permission in writing
`from the publisher.
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`Printed in the United States of America
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`10 9 8 7 6 5 4 3 2
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`ISBN 0-13-164319-3
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`Prentice-Hall International, Inc., London
`Prentice-Hall of Australia Pty. Limited, Sydney
`Editora Prentice-Hall do Brasil, Ltda., Rio de Janeiro
`Prentice-Hall Canada Inc., Toronto
`Prentice-Hall of India Private Limited, New Delhi
`Prentice-Hall of Japan, Inc., Tokyo
`Prentice-Hall of Southeast Asia Pte. Ltd., Singapore
`Whitehall Books Limited, Wellington, New Zealand
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`Ex. PGS 1045
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`1.2 Computer Technology
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`The idea of using digital computers as components in control systems emerged around
`1950. Applications in missile and aircraft control were investigated first. Studies
`showed that there was no potential for using the general-purpose digital computers
`that were available at that time. The computers were too big, they consumed too much
`power, and they were not sufficiently reliable. For this reason special-purpose com(cid:173)
`puters-digital differential analyzers (DDA)-were developed for the early aerospace
`applications.
`The major developments in computer control occurred in the process industries.
`The progress of these developments is illustrated in Fig. 1.2, which shows the growth
`of computers used for process control over a period of 25 years.
`
`100M
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`10M
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`1M
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`100k
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`10k
`
`1k
`
`100
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`10
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`~
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`1! ! 0 u ....
`0 ...
`" ~
`~
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`Figure 1.2 Growth of computers used
`for industrial process control. For
`comparison the total number of
`computers is also given. The picture is
`compiled from several sources:
`Control Engineering, A. D. Little,
`Frost and Sullivan, and Diebold.
`(Redrawn from data published in
`Control Engineering, © 1980,
`Technical Publishing Co., with
`1990 permission.
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`1960
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`1g'l0
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`1980
`
`The idea of using digital computers for process control emerged in the mid(cid:173)
`fifties. Serious work started in March 1956 when the aerospace company Thomson
`Ramo Woolridge (TRW) contacted Texaco to set up a feasibility study. After pre(cid:173)
`liminary discussions it was decided to investigate a polymerization unit at the Port
`Arthur, Texas, refinery. A group of engineers from TRW and Texaco made a thorough
`feasibility study, which required about 30 people-years. A computer-controlled system
`for the polymerization unit was designed based on the RW-300 computer. The control
`system went on-line ~arch 12, 1959. The system controlled 26 flows, 72 temperatures,
`3 pressures, and 3 compositions. The essential functions were to minimize the reactor
`pressure, to determine an optimal distribution among the feeds of 5 reactors, to con(cid:173)
`trol the hot-water inflow based on measurement of catalyst activity, and to determine
`the optimal recirculation.
`The pioneering work done by TRW was noticed by many computer manufac(cid:173)
`turers, who saw a large potential market for their products. Many different feasibility
`studies were initiated and vigorous development was started. The results of these
`efforts are reflected in the growth shown in Fig. 1.2.
`To discuss the dramatic developments, it is useful to introduce four periods.
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`Sec. 1.2
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`Computer Technology
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`3
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`Ex. PGS 1045