Robust Disturbance Rejection in Uncertain Singular Systems Using Equivalent-Input-Disturbance Method Based on Output Feedback Control

A robust disturbance-rejection problem for an uncertain singular system is considered in this paper. An equivalent-input-disturbance (EID) method is applied to improve disturbance-rejection performance. At first, the disturbance estimation is obtained by the EID method; Then, the disturbance estimation is compensation to the control input channel to offset the adverse effect of external disturbance and uncertainties on the system. Two sufficient and necessary conditions using linear matrix inequality are obtained, which can guarantee the admissibility (regularity, non-impulsiveness, and stability) for the closed-loop control system. In addition, output-feedback control laws (static, dynamic) and observer gain are obtained using the singular value decomposition method. A numerical example and simulation studies prove the validity and feasibility of the presented method.