Principal Gains and Phases: Insensitive Robustness Measures for Assessing the Closed-Loop Stability Property

摘要

An improved version of the principal gain phase method for assessing the robustness of the closed loop stability property is presented. Two lemmas which combine to give improve bounds and which are derived from the bound conditions theorem in the original principal gain phase method are demonstrated. The results are established for a multiplicative type perturbation before the plant, but the same arguments can be used to derive similar results for either a multiplicative type perturbation after the plant or an additive plant perturbation. Conditions for which the principal gain phase method is insensitive to small system perturbations are derived.