Almost Decoupling by Quantitative Feedback Theory

Abstract

This paper uses almost decoupling theory to obtain a systematic solution to the MIMO-QFT problem by an n times solution of the SISO-QFT sensitivity constraint problem. This is similar to the current MIMO-QFT formulation that requires in principle an n times solution for the elements of the closed-loop transfer matrix. The problem is also in a form where direct comparison with H ∞ control is feasible. However, due to the use of unstructured perturbation description, this design route along with all H ∞ based design methods will invariably produce more conservative (higher bandwidth) controllers than classical QFT .