Stabilization of discrete singularly perturbed systems under composite observer-based control

New stability conditions for discrete singularly perturbed systems are presented in this study. The corresponding slow and fast subsystems of the original discrete singularly perturbed system are first derived. The observer-based controllers for the slow and the fast subsystems are then separately designed and a composite observer-based controller for the original system is subsequently synthesized from these observer-based controllers. Finally, a frequency domain e-dependent stability criterion for the original discrete singularly perturbed system under the composite observerbased controller is proposed. If any one condition of this criterion is fulfilled, stability of the original systemby establishing that of its corresponding slow and fast subsystems is thus investigated. An illustrative example is given to demonstrate that the upper bound of the singular perturbation parameter e canbe obtained by examining this criterion.