A robust nonlinear controller with application to a magnetic bearing system

In this paper, a robust nonlinear controller for a nonlinear system subject to model uncertainties is proposed. This controller consists in the association of a "robust feedback linearization" with a robust linear H. controller. The robust feedback linearization yields a linear system equal to the linear approximation of the original nonlinear system around a nominal operating point. The robustness of the resulting overall nonlinear controller is proved by theoretical arguments and illustrated through an application example. The advantage of the robust feedback linearization with respect to the classical one is emphasized.