STABILITY ROBUSTNESS FOR DECENTRALIZED CONTROL-SYSTEMS

In decentralized control systems, a control structure or variable pairing satisfying the nominal stability and integrity requirements, by means of the RGA and NI, can be rather risky in the presence of inherent model mismatch. In this paper, a stability robustness measure, based on mathematical and geometrical analysis of the behaviour of the NI and RGA in the face of model uncertainties, is developed. In contrast to existing methodology, rigorous justification is provided and more important insights into the interpretation and application of the measure are offered. The approach used also applies to the general case of multiple gain errors and a general stability condition is presented for 2 x 2 systems.