Unknown input observer based robust control for fuzzy descriptor systems subject to actuator saturation

Abstract : For the stabilization problem of non linear system, a new control based on unknown input observer (UIO) is proposed to consider unknown inputs and actuators saturation. The proposed control method consists of designing an H∞ control for nonlinear systems based on TS fuzzy systems subject to unknown inputs and actuators saturation using the idea of UIO. To estimate state variables and unknown inputs, the unknown input observer is investigated. The saturation effect is considered through the polytopic representation. The descriptor representation is used to derive the new robust stabilization conditions of closed-loop system with unknown and constraints inputs. Both the UIO and controller gains are formulated as an optimization problem, which is expressed under Linear Matrix Inequalities (LMI). Simulations results are given to show the effectiveness of the proposed method.