Robust PI controller design for an uncertain recycle system

In this paper, a new approach is proposed for design of a robust controller for interval process systems in the presence of parametric uncertainties. The proposed method uses a necessary condition and sufficient condition for stability of interval polynomial. These conditions are used to derive a set of inequalities in terms of the compensator parameters which can be solved to obtain a robust controller. The proposed method is simple, involves less computational complexity and provides an easy method to obtain a robust compensator. The proposed method is applied to design a robust proportional-integral controller for a recycle system in the presence of process gain uncertainties. The results show the efficacy of the proposed method.