Signal processing for active control [Book Review]

by Stephen Elliott, Academic Press 2001, 511 pp., ISBN 0-12-237085-6, $89.95. Reviewed by Sean Wellington, Southampton Institute, U.K. This useful book is written in an accessible textbook style and provides a thorough treatment of the theory and practice of active control system design. Chapter 1 introduces the physical principles of active control, in particular, analytical models of various physical systems. The emphasis throughout is on active sound and vibration control systems. Chapter 2 presents optimal and adaptive digital filters, starting from an introductory level, but moving quickly to cover optimal and adaptive FIR and IIR filters. LMS, RLS, and frequency domain adaptation schemes are analyzed and compared. In chapter 3, the design of single-channel feedforward controllers for deterministic and stochastic disturbances is introduced, whereas chapters 4 and 5 consider multichannel control of tonal and stochastic disturbances, respectively. Application examples include controlling propeller noise in fixedwing aircraft and controlling road noise in vehicles. Chapter 6 draws together many of the key issues in the design of feedback controllers, both analog and digital. The work is then extended to consideration of adaptive feedback controllers in chapter 7 and control of nonlinear systems in chapter 8. This progressive development is particularly helpful for those approaching the subject for the first time. The last two chapters provide further coverage of practical implementation issues. Chapter 9 considers the optimal positioning of transducers, in particular, sensors for feedback and feedforward control and actuators for active sound or vibration control. Finally, chapter 10 provides an introduction to controller hardware, including data conversion and finite wordlength effects. The book is very well structured and provides a rigorous analytical treatment of the subject matter. Each section is illustrated with appropriate practical applications. The book benefits from the use of a unified system of notation throughout. This, combined with the comprehensive glossary of symbols and notation, means that the material is very accessible to the reader seeking to make use of only one chapter or section. Stephen Elliott has drawn upon his extensive experience to present a comprehensive, yet accessible, treatment of the theory and practice of active control system design. The text will be of real benefit to researchers and practicing engineers, while some of the sections will also be of interest to advanced undergraduate students.