ABSTRACT
Quantitative feedback theory (QFT) is a robust control engineering design methodology that uses the feedback to simultaneously and quantitatively reduce the effects of plant uncertainty and satisfy performance control specifications. QFT has been successfully applied to a wide variety of control problems, including stable and unstable plants, minimum and non-minimum phase systems, single-input single-output and multiple-input multiple-output processes. QFT is a multi-criteria and transparent control engineering methodology. It quantifies the balance among the controller structure, cost of feedback, performance specifications, and model plant uncertainty at each frequency of interest. This chapter summarizes steps of the QFT methodology along with an illustrative example of a DC motor. Afterward, an additional case of an airplane flight control system shows more details of the methodology. The chapter explains how to apply QFT to model-matching control systems, feed-forward control strategies, and PID design and tuning. Finally, it discusses some practical QFT control design tips.
