Nonlinear repetitive control

Repetitive controllers are generally applied to reject periodic disturbance s and to track periodic reference signals with a known period. Their design is based on The Internal Model Principle, proposed by Francis and Wonham. This paper describes a new finite-dimensional SISO repetitive controller fo r two different classes of nonlinear plants. Simulation results show asympt otic tracking of the periodic reference signal by the proposed repetitive c ontroller in closed loop up to the Nth harmonic frequency. A proof of robus tness of the repetitive control system to small nonlinearities, like actuat or nonlinearities, is provided.