The Parametrization of All Stabilizing Modified Repetitive Controllers for Non-Minimum Phase Systems

In the present paper, we give the parametrization of all stabilizing modified repetitive controllers for non-minimum phase systems. The basic idea to obtain the parametrization of all modified repetitive controllers for non-minimum phase systems is very simple. If the repetitive controller stabilizes the plant, then the repetitive controller must be included in the class of all stabilizing controllers for the plant. The parametrization of all stabilizing controllers for the plant, which is not necessarily repetitive controllers, are obtained by Youla et al. and Vidyasagar. The parametrization of all stabilizing controllers includes a free parameter, which is stable. That is, stabilizing repetitive controllers for non-minimum phase systems can be designed using the free parameterin the parametrization by Youla et al. and Vidyasagar. Using this idea, we obtain the parametrization of all stabilizing modified repetitive controllers for non-minimum phase systems. Next, a numerical example is illustrated to show the effectiveness of the proposed parametrization.