Gradient-based Takagi-Sugeno fuzzy local observer

In this paper, a recently introduced nonlinear gradient-based observer [1] has been adopted for Takagi-Sugeno (TS) fuzzy systems. The designed observer is especially aimed to estimate the unmeasurable states of the TS fuzzy systems where the LMI solution is not feasible to find the observer gains. The estimation of gradient observer is evaluated based on the Levenberg-Marquardt direction where the local convergence property is guaranteed using Lyapunov function approach. The numerical simulations present accurate estimation results for TS fuzzy nonlinear systems including a comparison with the conventional Extended Kalman Filter (EKF) yielding acceptable results.