GAIN-BANDWIDTH OPTIMAL DESIGN FOR THE NEW FORMULATION QUANTITATIVE FEEDBACK THEORY

摘要

Recent work in Quantitative Feedback Theory (QFT) has extended the methodology to both parametric and non-parametric uncertainty. An issue that remains largely unsolved is that of constructive existence conditions for optimal QFT controllers. The approach of Thompson and Nwokah (1994) was to build upon the classical Bode analysis approach to loop shaping by defining the structure and parameters of an acceptable initial QFT controller a priori; locally optimal controllers of this structure could then be computed via a constrained nonlinear programming algorithm. The purpose of this paper is to extend this methodology to the combined parametric and non-parametric, new formulation QFT bounds. In addition, we take a closer look at measures of optimality for the QFT problem, and we consider Horowitz's original notion of "cost of feedback" in terms of a quantity we define as controller excess gain-bandwidth area.