Iterative learning controller for linear systems with a periodic disturbance

An iterative learning controller is proposed for systems whose transfer functions have arbitrary relative degree and the role of the high-order derivative of the output error is analysed in connection with the relative degree. In the case of a linear time-invariant system with a periodic disturbance a sufficient condition for the convergence of the output error is derived. It is demonstrated, by simulation, that the proposed controller yields a good performance even in the presence of a periodic disturbance.