Digital stabilization of nonlinear time-delay systems and its robustness

This paper is concerned with digital control and robust stability for stabilizing nonlinear time-delay systems, in which hunting will often occur. First a new digital controller for stabilization is proposed, which is more effective than the usual Smith method. Next, the error function due to the identified error of dead time is derived, by which the robust stability condition is obtained in discrete time-delay systems. Finally, by applying a new digital controller to the electropneumatic valve positioner, it is confirmed through simulation and experimental studies that both the controller and its robust stability analysis are valid