An Analysis of Robust Stability Conditions for Multivariable Systems with Unstructured Uncertainties by Use of IMC

In this paper it is demonstrated how conditions for guaranteeing robust stability for multivariable systems with unstructured uncertainties represented as single perturbations may be derived through the use of an Internal Model Control (IMC) scheme. The presented development provides a methodology for obtaining robust stability conditions for systems with unstructured uncertainties, and gives further insight into the relations between the stability conditions for the different uncertainty representations.