Exact repetitive control of minimum phase linear systems

A novel repetitive control scheme for minimum phase linear systems, which achieves asymptotic output tracking over the whole frequency range, is proposed. It is composed of two parts. The first is a system described by a continuous time difference equation, which asymptotically generates the required exact tracking control. The second one is a system described by ordinary differential equations and time-lag elements, which, through system inversion, online estimates the delayed input. This estimate is then fed back to obtain an exponentially stable closed - loop control scheme, which is robust with respect to linear plant perturbations.