Abstract
In this paper, we treat the repetitive control for linear mechanical systems in the discrete domain. First, we investigate the stability of the repetitive control system using the basic feed-back control theorem and note that the stability condition can be related to the positive real condition. We next propose an available control algorithm based on the concept of positive real property for the plant whose transfer function is not positive real (e.g. a strictly proper transfer function). The value of parameters in the algorithm can be found by using the Nyqist plots. We also discuss the characteristics of the designed system and present some results of hybrid computer simulations for a mechanical system. It is shown that the designed repetitive control system is insensitive to changes in plant parameters and the error converges in spite of the high frequency of the reference signal.
