STABILITY MARGIN EVALUATION FOR UNCERTAIN LINEAR-SYSTEMS

A sufficient stability condition for parameter variation in a perturbe d, continuous time, multivariable linear system, represented by a stat e space model is presented. Starting with the existence of an algebrai c Riccati equation, a stability bound is derived from the polar decomp osition of the nominal system matrix. Unlike previous work, the result s are not dependent on the solution of the Lyapunov equation and, cons equently, not a function of an arbitrarily selected positive definite matrix. In addition, the bound would appear to be the tightest possibl e, in that violation of the presented inequality can be shown to lead to instability.