Model reference feedback and PID control for interval plants

The physical parameters of controlled systems (plants) are uncertain and are accompanied with nonlinearity. The transfer function of the controlled system should, therefore, be expressed by interval polynomials. This paper describes the realization of robust control for that type of plant (interval system) via model reference feedback, and discusses the relationship between the feedback structure and the conventional PID control system. Robust performance of the feedback control system is evaluated by using a discrimination method of characteristic roots area on an s-plane. In this paper, we present designing examples of a robust control system via model reference feedback which corresponds to a high-gain feedback and a kind of PID control