Parametric and unstructured approach to uncertainty modelling and robust stability analysis

Abstract

The paper deals with comparison of two principal approaches to uncertainty modelling and related robust stability analyses for a system with uncertain time-delay. A paper bleaching process, used as a testing plant, is described first as a system with parametric uncertainty and then in the form of unstructured multiplicative uncertainty model. The robust stability or instability of closed control loop with appropriate uncertain model of the controlled system and selected controller is verified and obtained results are compared. Moreover, the issue of conservatism in uncertainty description and in subsequent robust stability analysis is also discussed.