Robust Hybrid PI Controller with a Simple Adaptation in the Integrator Reset State

Abstract

In this paper, we consider the implementation and the robust stability analysis of a new hybrid PI controller. Two laboratory processes are used, one to control the level in water reservoir system with capacity of 200 liters, and the other to control the temperature in a continuous oven of one meter long. The robust stability analysis conditions are proposed in terms of convex optimization procedures and can be used to certify the robust closed-loop stability. The dynamics of the processes are approximated by a first order system plus delay and, because of this, a Smith predictor is jointly used with all controllers. Concerning the hybrid PI implementation, we compare the performances achieved by a classical linear PI, by a hybrid controller found in the literature and by a new hybrid controller with adaptation of the reset value. We illustrate the performance, robustness and disturbance rejection of all three controllers in a prototype by control real time tests. The achieved performance of each controller is quantified by means of typical industrial indexes.