Linear functional observer design for unknown input system and its application to disturbance attenuation problems

This paper presents a reduced-order state-function/unknown input observer for linear unknown input systems with additional H_infin performance. The proposed reduced-order observer can be designed under a less strict existence condition. The control scheme which can be estimated unknown inputs and decoupled disturbance, simultaneously, is also proposed, and is applied to disturbance attenuation problems. Experimental results on robot control are shown to confirm the properties of the proposed reduced-order observer