H∞ Observer-Based Controller for Lipschitz Nonlinear Discrete-Time Systems

Within the paper, a relevant H-infinity observer-based controller design for a class of Lipschitz nonlinear discrete-time systems is proposed. Usually, Bilinear Matrix Inequaities (BMIs) are obtained from the resolution of the observer-based stabilization design problem for this class of systems. Since, the resolution of a BMI is a hard task, then it is interesting to search for a convenient way to linearize the obtained conditions. Therefore, the objective of this paper is to present new Linear Matrix Inequality (LMI) conditions ensuring the convergence of the observer-based controller in a noisy context. Thanks to the introduction of a slack variable the presented LMI conditions are more general and less conservative than the existence ones. Indeed, reformulations of the Lipschitz property and Young's relation in a convenient way lead to a more relaxed new LMI. A numerical example is implemented to show high performances of the proposed design methodology with respect to some existing results.