A Historical View of Multivariable Frequency Domain Control

The late sixties and early to mid seventies saw and explosion of interest and innovation in the area of frequency domain methods in the analysis and design of multivariable control systems. The emergence of multivariable frequency domain control design techniques in the 1960’s and 1970’s was based on traditional views of the role of the designer in the design process. Classical influences on the emerging Nyquist and root-locus theory were therefore natural and, it can be argued, very successful. This paper presents a personal review of the ideas, concepts and techniques from the perspective of a researcher active in the area at the time. The paper will aim to provide a personal insight into the issues and provide an opportunity for young researchers to review the wide range of contributions made before the current use of H-infinity (and related optimisation) methods become so prevalent. Copyright © 2002 IFAC