Strong robustness in uncertain multivariable systems

A review is presented of the basis of the Horowitz quantitative feedback theory (QFT). It is shown that the basic assumptions of (QFT) have mathematical justification. However, necessary and sufficient conditions for the solvability of the QFT problem are presently not known. By reposing the QFT problem as an M-matrix design problem, it is possible to develop the desired existence conditions as well as simplify the design of the controllers which solve the QFT problem. Some preliminary results are presented and form the basis of ongoing work into the automation of the QFT design process.<
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