Introduction to Quantitative Feedback Theory for lateral robust flight control systems design

Abstract

Quantitative Feedback Theory (QFT), is a frequency-domain-based robust control design approach that was developed in the early 1970s and has received considerable attention over the past two decades. In the last few years, its application to aircraft flight control systems design has been widely investigated. In this paper the basic concepts, principles, design procedure, and features of QFT are reviewed and summarized for single-input single-output systems. Its application to a lateral flight control system design is then considered. A robust roll-attitude control system is designed to cover a certain operating range using the QFT methodology, and certain eigenstructure-assignment results. The integration of QFT with eigenstructure methods results in a controller with the stability and performance robustness of QFT design, and the decoupled dynamic responses of an eigenstructure-assignment approach. The results indicate QFT has significant potential in robust flight control systems design. The combination of techniques should be applicable to other industrial sectors.