Page 16 - Modern Control Systems

xii Preface

Control engineering is an exciting and a challenging field. By its very nature, con-
trol engineering is a multidisciplinary subject, and it has taken its place as a core
course in the engineering curriculum. It is reasonable to expect different approaches
to mastering and practicing the art of control engineering. Since the subject has a
strong mathematical foundation, we might approach it from a strictly theoretical
point of view, emphasizing theorems and proofs. On the other hand, since the ulti-
mate objective is to implement controllers in real systems, we might take an ad hoc
approach relying only on intuition and hands-on experience when designing feed-
back control systems. Our approach is to present a control engineering methodology
that, while based on mathematical fundamentals, stresses physical system modeling
and practical control system designs with realistic system specifications.
We believe that the most important and productive approach to learning is for
each of us to rediscover and re-create anew the answers and methods of the past.
Thus, the ideal is to present the student with a series of problems and questions and
point to some of the answers that have been obtained over the past decades. The
traditional method—to confront the student not with the problem but with the fin-
ished solution—is to deprive the student of all excitement, to shut off the creative
impulse, to reduce the adventure of humankind to a dusty heap of theorems. The
issue, then, is to present some of the unanswered and important problems that we
continue to confront, for it may be asserted that what we have truly learned and
understood, we discovered ourselves.
The purpose of this book is to present the structure of feedback control theory
and to provide a sequence of exciting discoveries as we proceed through the text
and problems. If this book is able to assist the student in discovering feedback con-
trol system theory and practice, it will have succeeded.

WHAT'S NEW IN THIS EDITION

This latest edition of Modern Control Systems incorporates the following key updates:
• A new section in Chapter 1 on green engineering. The role of control systems in green
engineering will continue to expand as global environmental challenges require ever
increasing levels of automation and precision.
• New design problems in key chapters that illustrate control design to support green
engineering applications, such as smart grids, environmental monitoring, wind power
and solar power generation.
Q A new section in each chapter entitled "Skills Check" that allows students to test their
knowledge of the basic principles. Answers are provided at the end of each chapter for
immediate feedback.
• A new section on the negative gain root locus.
• A new section on PID tuning methods with emphasis on manual tuning and Ziegler-
Nichols tuning methods.
• Over 20% of the problems updated or newly added. With the twelfth edition we now
have a total of over 1000 end-of-chapter exercises, problems, advanced problems,
design problems, and computer problems. Instructors will have no difficulty finding
different problems to assign semester after semester.
• Video solutions of representative homework problems are available on the companion
website: www.pearsonhighered.com/dorf.