Simultaneous measurement noise and unknown input reconstruction based on reduced-order observer and high-gain differentiator

This paper considers the issue of the measurement noise and unknown input reconstruction based on reduced-order and high gain sliding mode observers. An augmented vector which consists of the state vector and measurement noise vector of original system is constructed, and an augmented system is proposed based on the augmented vector. Then, a reduced-order observer which can not only estimate the state of the system but also reconstruct the measurement noise vector is developed. A high-gain exact differentiator is considered to estimate the system output derivatives. A kind of simultaneous unknown input and measurement noise reconstruction method is proposed. Finally, a simulation example is given to illustrate the performance of the proposed methods.