Unknown Input Observer based Sliding Mode Control for System with Mismatched Disturbance

Abstract:

This paper considers a control approach for a nonlinear system with mismatched disturbances via the estimation of system states and unknown inputs reconstruction. First, under the assumptions that both states and unknown disturbance are measurable, a new sliding mode controller is proposed to stabilize the output of the system. Then, by designing a kind of unknown input observer (UIO), a time varying unknown inputs reconstruction method is established. Meanwhile a set of high gain sliding mode observers are considered to obtain the derivative information of system outputs and the unknown disturbance in finite time, which will be further used in reconstructing the disturbance and designing control strategy. Subsequently, a new observer based controller is developed and its feasibility is proved. At last, a simulation example to a real model is given to verify the effectiveness of the proposed controller.