Linear model reduction using Hurwitz polynomial approximation

Abstract

A new approach to stable reduced-order linear model construction is given, based on the concept of Hurwitz polynomial approximation. Padé approximants to the tangent function of a given large-degree Hurwitz polynomial are constructed, such that the corresponding low-degree polynomials are also Hurwitz. We prove a theorem to that effect and give methods for obtaining the reduced Hurwitz polynomials. Model reduction is achieved by first invoking this theorem and completing the reduction using the Padé equations. Two examples are given.