Wireless Secure Communication of Chaotic Systems Based on Takagi–Sugeno Fuzzy Optimal Time Varying Disturbance Observer and Sliding Mode Control

This paper presents a new application of the secure communication system (SCS) of the chaotic systems with experimentally verification of wireless devices together with a new stability condition of disturbance observer, which is used to reject the attack signals on public channels and uncertain values on both master and slave of the secure communication system. To ensure the security of the text message transmission, the states of two nonidentical chaotic systems are used to encrypt and decrypt the signal, respectively. To synchronize the slave and master, first, the Lorenz chaotic system is remodeled into the Takagi-Sugeno fuzzy (TSF) model for softening the designs of the controller and observer. Second, to meet the requirement of the sent and received signals are identical, the synchronization controller was designed based on the adaptive sliding mode control (SMC). The adaptive laws of the controller are based on the regulating boundary of saturation thickness. Third, to prevent the attack signals on the public channels and the variations of the system parameters, the disturbance observer (DO) was newly proposed. This is a new contribution of the paper to the area of disturbance observer design. Fourth, the stability of the proposed control method was proved using the Lyapunov condition. Final, the performances of the proposed method are demonstrated via simulation using MATLAB software and experiment using the chips WiFi ESP8266 Shields. The obtained results with attacked signals and parameter’ variations were mostly rejected both in simulation and experimental studies. The states of MSSs are identical. Therefore, the sent and received data are completely secured and identical.