Robust variable structure control of uncertain systems with disturbance attenuation

Robust variable structure controller design is discussed for uncertain systems with unmatched model perturbations and unknown external disturbances. The proposed variable structure controllers guarantee the state variables of the systems to reach the switching hyper-plane in finite time, and to remain on it thereafter, By applying robust control theory, the sliding modes in the variable structure systems are designed, such that with the existence of model perturbations and external disturbances, the sliding modes remain stable, and the impact of external disturbances on the system outputs satisfies prescribed performance index.