BIBO stability robustness in the presence of coprime factor perturbations

A necessary and sufficient condition for robustly stabilizing a family of plants described by perturbations of fixed coprime factors of a plant is given. The computation of the largest stability margin is discussed via solving a nonsquare l/sup 1/ optimal control problem. An algorithm for obtaining lower approximations of the minimum value of the optimization problem mu /sub 0/ is proposed. This, together with the standard algorithm which provides upper approximations, allows mu /sub 0/ to be computed within any degree of accuracy.<
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