Reducing unstable linear control systems via real Schur transformation

An algorithm is proposed to generate reduced order models of linear unstable control systems. The real Schur transformation is used to decompose a system into an interconnection of stable and unstable subsystems. The stable subsystem is then reduced, via a chosen model reduction algorithm, by taking the effect of the unstable subsystem into account. Computer simulation results are presented to illustrate the effectiveness of the proposed model reduction method.