Robust stability in multivariable feedback systems using dominance concept and approximate model

One of the fundamental problems in the advanced control system design is the uncertainty in the model description. Moreover, multivariable systems have complementary difficulty because of the interaction effects between different control loops. In this case the regulator requirements are complicated. The paper presents frequency-domain approach to design robust regulator when the detailed plant model is replaced by suitable approximate one. The difference between the step responses of the plant and the approximate model is used to present the measure of plant uncertainty. As a result the conditions are defined which guarantee the stability of the real system despite the existing uncertainties