A design method for simple repetitive controllers for time-delay plants

The modified repetitive control system is a type of servomechanism for the periodic reference input. Using previously proposed modified repetitive controllers, even if the plants does not includes time-delay, the transfer function from the periodic reference input to the output and that from the disturbance to the output have an infinite number of poles. From the practical point of view, it is desirable that the transfer function from the periodic reference input to the output and that from the disturbance to the output have a finite number of poles. Yamada et al. proposed the concept of simple repetitive control systems such that the controller works as a modified repetitive controller and the transfer function from the periodic reference input to the output and that from the disturbance to the output have a finite number of poles. In addition, Yamada et al. clarified the parametrization of all stabilizing simple repetitive controllers. However the method by Yamada et al. cannot be applied for time-delay plants. The purpose of this paper is to propose the parametrization of all stabilizing simple repetitive controllers for time-delay plants.