Design of Functional Observer for Linear System with Unknown Disturbance and Its Application to Disturbance Attenuation

This paper presents a reduced-order functional observer for linear system with unknown disturbance from H_infin performance point of view. The proposed reduced-order functional observer can be designed under a less strict existence condition. The controller scheme based on the proposed functional observer can simultaneously estimate a state-function and unknown disturbance, and can be applied to disturbance attenuation problems. Numerical example is given to illustrate the properties of the proposed reduced-order functional observer