“…A repetitive control system is a type of servomechanism for a periodic reference input for the periodic signal without steady state error (Inoue et al, 1981;Omata et al, 1987;Watanabe and Yamatari, 1986;Hara et al, 1988;Yamamoto and Hara, 1988;Nakano et al, 1989;Ikeda and Takano, 1990;Yamamoto and Hara, 1992;Yamamoto, 1993;Katoh and Funahashi, 1996;Weiss, 1997). That is, the repetitive control system follows the periodic reference input without steady state error, even if there exists a periodic disturbance or the plant has uncertainty (Inoue et al, 1981;Omata et al, 1987;Watanabe and Yamatari, 1986;Yamamoto and Hara, 1988;Nakano et al, 1989;Ikeda and Takano, 1990;Yamamoto and Hara, 1992;Yamamoto, 1993;Katoh and Funahashi, 1996;Weiss, 1997). The repetitive control system was proposed for 'high accuracy control for magnet power supply of proton synchrotron in recurrent operation' (Inoue et al, 1981).…”