Book Reviews
B. C. Kuo, Digital Control Systems,
Holt, Rinehart and Winston, Inc.,
York, 1980. 730 pp., $27.85.
New
Reviewed by Chin-Shung Hsu
Significantprogress made during recentyears in the numerical aspects of
controlandsystem
theory as well as
microcomputer technology
prompts
a
great desire to develop a digital control
courseforundergraduateseniors.This
will not only introduce students to a new
dimension of technical knowledge which
undoubtedly is of paramount importance
in industrialapplications, but will also
offer students an invaluable opportunity
to appreciate the significance of control
theory via digital implementation. Envisaged as above, ProfessorKuo’s new
revisionof
his book Digital
Control
Systems(1977)(hereafter calledKuo’s
book) isatimely and welcomeupdated
text.
Kuo’s book contains fourteen chapters, most of which can be comprehended
without much difficulty by readers with
some knowledge of matrix algebra, Laplace transforms, andthe basic principles
offeedbackcontrolsystems,
including
state-variableanalysis.
Microprocessor
programming ability is not essential until
the last chapter.
The subject matter in Kuo’s book may
be divided into four major topics, namely,mathematicalbackground,
modeling
and analysis, digital designandsimulation,and
microprocessor
implementaIn what follows,each
topic is
reviewed:
Math Background: The main
tools used in the text are Z-transforms, signalflow
graphs, and
some matrix theory in the context
of discrete state equation (set of
first-orderdifferenceequation);
these topics are covered in detail
in Chapters 3 and 4.
ModelingandAnalysis:
Mathematical treatments of A/D, D/A
conversion,
sample-and-hold,
andsampling
process arepresented in Chapter 2, analysis of
digital
control
systems
(both
sampledataandall
digital) is
extensively discussed. Topics included are Chapter 5 (Jury’s stability test, Lyapunov’s direct
method), Chapter 9 (controllabil-
ity and observability theorems for
linear time-invariant/time-variant
systems), Chapter 7 (time-domain
8 (freanalysis),
and
Chapter
quency-domain analysis).
(111) Digital Design and Simulations:
Computer simulations of sampledatacontrolsystems,
numerical
integrationand Z-formapproximation are dealt with in Chapter
6. Various design techniques are
delineated in Chapter10(feedbackcompensator,
digital controller and realization, root-locus
design, PID controller, state and
output feedback
pole
assignment),Chapter 13 (fulland reduced-order
observer
design),
Chapter 11 (discrete minimum
principle), and Chapter 12 (linear
regulator design).
(IV) Microprocessor Implementation:
The last chapter in Kuo’s book is
dedicated to the basic components
and programmingofmicroprocessors with their control applications. It deserves to be mentioned
herethat afew goodexamples
as
employing
microprocessors
digital controllers are included in
problem set at the end of preceding chapters.
It is this reviewer’s opinion that Kuo’s
students
book is verywellwrittenand
using it (if possible, along with computer
simulations and pP programming on-line
control
experiments)
will enjoy the
overwhelmingly
“applicable”
control
theory. And assuch,
Kuo’s book is
highly recommended as a senior level
text and asa reference book for engineers
who are interestedinlearningthebasic
principles of digital control systems.
Chin Shung Hsureceivedhis Ph.D. degree
fromOregon State Univ. in 1978. He is
currently an AssistantProfessorof
EE,
Washington State University, Pullman,
Washington. His researchinterestsinclude
bilinear control systems,
digital
control,
large-scalesystems and theoretic control in
immunology.
R. C. Dorf, ModernControlSystems, 3rd ed., Addison-Wesley,Reading, Mass., 1980. 493 pp.
Reviewed by Bruce K . Walker
This isthethirdedition
of apopular
text on classical control theorydirected
18
primarily at senior levelundergraduate
students and practicing engineers with no
previous background in control theory.
The material presented is along the lines
of [ 1-41 and the first 10 chapters of 1.51.
Topicsincludethe
modelling of linear
systems,
Laplace
transformation,
advantages and drawbacks of feedback,
classical rootlocus
and frequency domainanalysis, Nyquist and Routh-Hurwitz stability analysis,
state
variable
techniques,
compensation,
and
digital
control. In general, the depth of coverage
is not great, but abriefperusal
of the
topic list above reveals the considerable
breadth of coverage.
The newestedition
differsfrom
its
predecessors primarily in three respects.
A chapter on discrete-time systems
has
been added. The treatment
ofstate variablesandtimedomain
methods has
beenexpanded.Finally,
the book contains completely revamped problems for
all chapters.
The first chapter is awell-referenced
“tour” of some present day applications
ofcontroltheory.The
history of theoreticaladvances is described primarily
through the specific real-world problems
which providedtheimpetus
for them.
Examples and problems in this and later
chaptersspan numerous fields of specialization and usually concern contemporary systems.
Chapter 2 deals very briefly with
mathematical modellingofcontinuous
timesystems
by differential equations
derivedfrom basicphysicalprinciples.
As in previous editions of the text, the
treatmentof modellingis so brief that
most undergraduate students require supplemental material in order to grasp the
concepts. Following a concise section on
linearization,thechapter
developsthe
Laplace
transform
approach to linear
systemanalysisandusesthe
results to
derive transfer functions fora wide range
of thematerial(e.g.,the
convolution
property of Laplacetransformsis
not
of the material (e.g. the
convolution
propertyofLaplacetransforms
isnot
2 concludes
evenmentioned).Chapter
with concise sections on blockdiagram
and signal flow graph analysis and a short
introduction
computer
to
simulation
techniques, both analog and digital.
Chapters 3 and 4 concern theperformance of feedbackcontrolsystems.
Chapter 3 demonstrates clearly how
feedback can be used to rejectdisturbancesand variations in thesystem parameters and also to improvetransient
and steady state performance. Chapter 4
discusses classical
the
second-order
system response function in some detail
and defines the specifications related to
it. This chapter also defines system type
and
describes
its
relationship
to the
5 is ashort
steadystateerror.Chapter
chapter
Routh-Hurwitz
on
stability
analysis and the interpretation of s-plane
rootlocations in terms of the transient
response of a system. These three chapters are well-written and the material is
well covered.
Chapter 6 develops the root locus approach to system analysis. Theprocedure
is motivated conceptually, then each of
the properties of the root locus plot are
demonstrated for the generalcase. Finally, a number of examplesarepresented to illustrate the use of the method.
A rather complicated section on parametersensitivityconcludes
this chapter.
The problems at the end of this chapter
include many of the most illustrative in
the book.
Chapter 7 coverspolarplots,Bode
diagrams, log
magnitude-phase
plots,
and the concept offrequency response.
The approach to this material is standard
and, in fact, suffers to some degree from
2 numerical
a lackofexamples(only
examples are used in the entire chapter).
Chapter 8 does an excellent job of
presentingtheoften
difflcultmaterial
associated with Nyquiststability analysis.Complex
mappingtheoryandthe
techniques used in constructing the
Nyquistdiagramareclearly
explained
and illustrated. Also, the use of M and N
circles and the Nichols chart for closed
loop frequency response is demonstrated
concisely.Theuse
ofnumerical examples is again minimal.
Chapter 9 contains allof the discussion
of state variable techniques. It is unfortunatethat
thismaterialispostponed
until so late in the text. Also, in light of
therecentdevelopments
in frequency
domain analysis of multivariable systems
[6-71, it is unfortunate that this material
is developed independently from the
preceding chapters. Only token mention
is made of the important interpretation of
statevariables
asdescriptions
of the
internal behavior of a system. Finally, a
heavy emphasis is placed on theuseof
signal flow graphs for representation of
statevariablemodels whenanalogdiagramsandcanonicalforms
might be a
betterchoice. Discussions of the state
transition matrix, its properties and uses,
and how it is calculated are all more then
adequate. Several examples are included,
and an appendix is included for those
of matrix
readers requiring
review
a
algebra. The concepts of controllability
and observability are not discussed.
Chapter 10 discusses compensation
design. Phase-lead and phase-lag cascade
compensator design procedures are outlinedanddemonstrated by examples in
both the Bode domain and the root locus
domain. Compensator properties are also
discussed.
In
addition,
state
variable
feedbackfor minimumsquaredoutput
error and for pole placement purposes is
developed.
Chapter 11 is the newly added chapter
on discrete-time systems. A rather long
introductory sectionisfollowed by several extremely short sectionsthat cover
sampling,
zero-order
holds,
z-transforms, stability
and
performance
of
discrete-timesystems,anddigitalcompensation. The coverageof these topics is
reallytooconcisefor
theintroductory
role of the book.
Each chapter is followed by numerous
problems to be solved, some of which are
excellent for instructional purposes. Selected solutions appear at the back of the
book and a solution manual is available
from the publisher. One criticism of the
problems is that oftentimes, in an effort
to motivate each problem by a real-world
setting, the author has embellished some
problems with so much descriptivematerialthatthe
clarity and intent of the
problem become blurred (e.g., Problem
6.28 which
uses
two
paragraphs
on
automobile emissions to motivate a simplerootlocusproblem,
theresultsof
whicharenever
interpreted). Also, a
small number of solutions in the solution
manual are in error.
Ingeneral, the book is adequate for
introducingstudentsand
practicing engineersto thebasics ofcontrol theory
provided
supplementary
material
on
some topics is made available to them.
The book is not suitable as areference
text due toits lack of depth. The addition
of the new material is a positive
development, though thestate variableand
discrete-time control chapters coulduse
improvement.
B . C. Kuo. AutomaticControlSystems. 3rd ed., Englewood Cliffs, N.J.:
Prentice-Hall.1975.
AutomaticControl EnF.H.Raven.
gineering, 3rd ed., New York: McGraw-Hill,1978.
R. N. Clark. Introduction to Automaric
ControlSystems,
New York: Wiley,
1962.
J . J . D’Azzo and C. H. Houpis, Linear
Control System Analysis and Design,
New York: McGraw-Hill, 1975.
K. Ogata, Modern Control Engineering, Englewood Cliffs, N.J.: PrenticeHall,1970.
A. G.J . MacFarlane, B . Kouvaritakis,
& J . M. Edmunds, “Complex variable
methods for multivariable feedback
systemsanalysis
and design,” Proceedings on Alternatives for Linear
Multivariable Control, National Engineering
Consortium,
Chicago,
1977;
pp. 189-228.
A. G. J . MacFarlane (ed.), Frequency
Response Methods in Control Systems,
New York: IEEE Press. 1979.
Bruce K. Walker received the Sc.D degree
1980. He is presently an AsfromMITin
sistantProfessor ofSystems Engineering at
Case Western Reserve University, Cleveland,
OH.His
research interests include faulttolerant system
analysis
and control and
adaptive control. He is a member of IEEE and
AIAA.
CSM Announcements
Ten CSS Members Elected IEEE Fellows
Duringthe 1980 Decisionand Controla
Conference in Albuquerque, NM and
recent IEEE’s Fellow all.
Committee toannouncements ten css members were
elected as E E E Fellows. Below are their
names and Fellow citations, followed by
biography of those available atthe timeSpringValley,CA
ofthisissue’s
publication.CongratulaFor pioneering concepts and leadership
tions
Editor
in the development of computerized
control systems used in.process simLeonard 6. Gardner 11
ConsultingManufacturing Engr. Comulators and in automated production
lines.
puterized Systems
19