On the nonlinear ripple-free sampled-data robust regulator

In this paper, we present a control scheme for robust regulation of a discretized nonlinear system ensuring a ripple-free behavior in the intersampling time. We show that, as in the case of linear systems, the controller must contain an internal model to ensure that the continuous output tracking error decays asymptotically to zero. We also show that under certain conditions, a linear controller obtained from the discretization of the linear approximation of the nonlinear system, guarantees the robust regulation.