Table Of ContentNONLINEAR
CONTROL
of
ELECTRIC
MACHINERY
CONTROL ENGINEERING
A Series of Reference Books and Textbooks
Editor
NEIL MUNRO, Ph.D., D.Sc.
Professor
Applied Control Engineering
University of Manchester Institute of Science and Technology
Manchester, United Kingdom
Nonlinear Control of Electric Machinery, by Darren M. Dawson, Jun
Hu, and Timothy C. Burg
Additional Volumes in Preparation
Series Introduction
Many textbooks have been written on control engineering, describing new tech
niques for controlling systems, or new and better ways of mathematically formu
lating existing methods to solve the ever-increasing complex problems faced by
practicing engineers. However, few of these books fully address the applications
aspects of control engineering. It is the intention of this new series to redress this
situation.
The series will stress applications issues, and not just the mathematics of
control engineering. It will provide texts that not only contain an expose of both
new and well-established techniques, but also will present detailed examples of the
application of these methods to the solution of real-world problems. The authors
will be drawn from both the academic world and the relevant applications sectors.
There are already many exciting examples of the application of control
techniques in the established fields of electrical, mechanical (including aerospace),
and chemical engineering. We have only to look around in today’s highly auto
mated society to see the use of advanced robotics techniques in the manufacturing
industries; the use of automated control and navigation systems in the many arti
facts available to the domestic consumer market; and the reliable supply of water,
gas, and electrical power to the domestic consumer and to industry. However,
there are currently many challenging problems that could benefit from wider expo
sure to the applicability of control methodologies, and the systematic systems-
oriented basis inherent in the application of control techniques.
This new series will present books that draw on expertise from both the aca
demic world and the applications domains, and will be useful not only as academi
cally recommended course texts but also as handbooks for practitioners in many
applications domains.
Neil Munro
NONLINEAR
CONTROL
o f
ELECTRIC
MACHINERY
Darren M. Dawson
Clemson University
Clemson, South Carolina
Jun Hu
Seitroi, Inc.
Greenville, South Carolina
Timothy C. Burg
S. E. Huffman Corporation
Clover, South Carolina
Marcel Dekker, Inc. N ew York•
ISBN 0-8247-0180-1
The publisher offers discounts on this book when ordered in bulk quantities. For
more information, write to Special Sales/Professional Marketing at the address
below.
This book is printed on acid-free paper.
Copyright © 1998 by MARCEL DEKKER, INC. All Rights Reserved.
Neither this book nor any part may be reproduced or transmitted in any form or
by any means, electronic or mechanical, including photocopying, microfilming,
and recording, or by any information storage and retrieval system, without
permission in writing from the publisher.
MARCEL DEKKER, INC.
270 Madison Avenue, New York, New York 10016
http: //www. dekker. com
Current printing (last digit):
7654321
PRINTED IN THE UNITED STATES OF AMERICA
To My Parents
Jack and Carol Dawson
D. M. D.
To My Wife Jane
J. H.
To My Wife Karen
T. C. B.
Preface
In this book, we present several nonlinear control algorithms for a bench
mark mechanical system actuated by several different types of electric ma
chines. The motivation for this book came from what we like to call the
robot control man’s dilemma. Specifically, the typical robotics application
requires an electric machine to turn a robotic link along a desired position
trajectory. The procedure for designing a control algorithm to achieve a
desired position tracking performance specification typically involves the
following steps: (1) develop the nonlinear model for the mechanical subsys
tem dynamics of the robot manipulator and (2) develop a nonlinear torque
input control algorithm (i.e., assume that the link actuators are torque
sources) which provides a means of theoretically quantifying the link posi
tion control objective. After the nonlinear algorithm has been developed,
the control engineer usually performs simulations and discovers that the
algorithm works like a dream. He then decides that experimental valida
tion is required; however, he soon learns that most robots are not capable
of implementing his control algorithm because of some or all of the fol
lowing reasons: i) an archaic computer system - the control hardware is
not capable of implementing his nonlinear control algorithm, ii) torque or
current amplifiers not included - the control algorithm is designed for the
mechanical subsystem dynamics; hence, torque or current amplifiers are
required for implementation, iii) a geared robot - the encoder is mounted
on the motor side of the gear; hence, the link position measurements are
unknown if significant gear transmission dynamics exist, iv) what no ve
locity measurements? - most direct drive robots are only equipped with
link position measurements to save cost; furthermore, since tachometer-
based velocity measurements are usually very noisy, they are usually not
worth including. Fortunately, there are some direct drive robots equipped
with DSP computer systems and torque amplifiers which allow for control
implementation1.
After a year or so of implementing control algorithms on the above ro
botic hardware, the typical control engineer may find himself wondering
what a torque amplifier actually is. For the simple permanent brushed dc
1 Typically, the user still has to manufacture the velocity signal with a nonlinear
observer, a backwards difference algorithm, or some other sort of filter.
