Time-Varying Delay Compensation for a Class of Nonlinear Control Systems Over Network via H∞ Adaptive Fuzzy Controller

This paper introduces a robust H-infinity adaptive fuzzy controller for a class of unknown nonlinear systems over network. There are two main problems in the networked control systems, the time-varying networked-induced delay and the data packet dropouts. The time-varying networked-induced delays cause degradation for the system performance that controlled over network and also the system can be unstable. Moreover, the delay problem is aggravated when packet losses occur during the transmission of data. The proposed controller has a filtered error to handle the networked-induced delays. Furthermore, it is robust to overcome some packet losses. The unknown nonlinear functions of the system are approximated using fuzzy logic systems. The robustness of the proposed controller is achieved by combining the adaptive fuzzy controller with H-infinity control technique. The Lyapunov stability analysis is used to prove that the proposed controller is asymptotically stable. Stability of the whole closed loop system is guaranteed via the proposed controller in the presence of bounded external disturbance, data packet dropouts and time-varying networkedinduced delays. An extensive example of an inverted pendulum system is studied in detail to verify the effectiveness of the proposed controller based on TrueTime toolbox with comparative results.