Applied Control Theory for Embedded Systems
by Tim Wescott, Published by Newnes
ISBN 0-7506-7839-9, paperback, 320 pp, $59.95
This book presents control theory that is needed to do embedded systems controllers. It emphasizes the discrete frequency (z) domain, though it contains some s-domain (continuous frequency-domain theory) undersampling. It hits upon the major topics: basic feedback control, properties of linear systems, difference equations, Z transforms, system performance parameters, block-diagram algebra, frequency-domain stability analysis, compensator design, and sampling theory.
In addition to these essentials, the author also goes on to present nonlinear systems. Because there are so many kinds of nonlinearities, he presents some of the commonly-occurring ones, such as airplane control-surface speed-squared gain variation, hysteresis, actuator saturation, and stiction. The author’s experience at embedded control is revealed by giving some practical guidelines for solving design problems with these and other nonlinearities.
Final chapters also cover necessary topics in the practice of control design: measuring frequency response in actual systems, and handling numerical quantization that occurs in software, including limit cycles. He covers software numerical representation and the implementationof familiar functions numerically, as computer code. Some tools in the form of computer programs and segments of coded algorithms useful in implementing compensator filters are provided. Sample embedded code is given on the enclosed CD along with some analysis software.
I recommend this book for those who have already gone through basic continuous and discrete control and sampling theory. Although much of the essential mathematics is presented, it is somewhat rushed. Some derivations are hard to follow and must be worked out by the reader, guided by what is given in the book. For the engineer with some control design experience who wants a fuller grasp of control loops with μCs in them, this book is a supplementary text worth considering. It has enough content to merit its 320 pages, and would be a useful resource to draw from on the control section of the engineer’s library shelf.