Robust predictive extended state observer for a class of nonlinear systems with time-varying input delay

This paper deals with asymptotic stabilization of a class of nonlinear input-delayed systems via dynamic output-feedback in the presence of disturbances.The proposed strategy has the structure of an observer-based control law, in which the observer estimates and predicts both the plant state and the external disturbance.A nominal delay value is assumed to be known and stability conditions in terms of linear matrix inequalities are derived for fast-varying delay uncertainties.Asymptotic stability is achieved if the disturbance or the time delay are constant.The controller design problem is also addressed and a numerical example with an unstable system is provided to illustrate the usefulness of the proposed strategy.