Observer-based controller design for a nonlinear fractional order system

In this paper, an observer-based controller is introduced for a class of nonlinear fractional order systems. First of all, considering a stable linear fractional order system known as the reference model, the controller is designed so that the closed loop system tracks the states of the reference system. In most systems, some states are unmeasurable or unreachable, so the controller must be designed based on the observer. The observer has been suggested in this research, using the well-known differential mean value theorem approach, converts the nonlinear error dynamics of the observer into linear and parameters-varying, so that the stability analysis is done simply using the Lyapunov quadratic function and linear matrix inequality. The stability analysis of the observer-based controller is also performed using the Lyapunov theorem in the following section. Finally, the efficiency and effectiveness of the proposed controller are shown through the simulation results of two nonlinear fractional order systems.