Design of a discrete robust controller using a first-order model approximation

In this paper, a discrete controller with integral action is designed for a linear time invariant stable process based upon a first- order model approximation. Sufficient conditions in the form of simple inequalities are derived to ensure asymptotic stability. It is shown that this condition becomes both necessary and sufficient in the special case where the control interval approaches the open- loop settling time. The stability criterion is a closed- form inequality equation that is well suited for real- time calculation of the admissible controller parameter space.