Research On Sampled-data Synchronization Controller For Chaotic Secure Communication System With Data Missing

Chaotic system is an extremely complex nonlinear system, and the chaotic signal with the feature of natural concealment, unpredictability, quite sensitivity to initial values, noise-similarity, is very suitable for the secure communication systems. With the rapid development of digital computer technology, the sampled-data control systems attract widespread attentions, however, control inputs missing often occurs in real sampled-data control systems, which will seriously affect system performance or even destroy the stability of system. Therefore, the dissertation mainly studies the sampled synchronize control issue in chaotic secure communication systems with control inputs missing. The main contents of the dissertation are as below:Firstly, in the dissertation, a synchronized problem is investigated for the chaotic systems with control inputs missing in the condition of constant sampling period. The Hold-input strategy is used to transfer the missing data as input delays. In order to analyzing the stability of system, the error system is converted into error system with input delay by using input delay method. The gain of the designed controller and the maximum number of consecutive packet loss can be calculated by linear matrix inequalities (LMI) approach. Simulation results illustrate the effectiveness of the chaotic secure communication systems based on masking techniques.Secondly, for the chaotic synchronization control systems with control inputs missing, the zero-input strategy is adopted. Based on the switched system method and input delay method, the sampled-data error system with control inputs missing can be transferred into a switched delay system with both a stable subsystem and an unstable subsystem. Then the stability analysis is given based on average dwell time method. Meanwhile, the relation between sampling and convergence rate, data missing rate and convergence rate are discussed. The simulation results show that the synchronization time of two Chua’s circuit becomes shorter if data missing rate and the sampling period is smaller and the designed control method can be applied to the chaotic secure communication.Furthermore, considering time-varying sampling period in chaotic synchronization control system with control inputs missing problems, the zero-input strategy is adopted to establish a switched delay system with both stable and unstable subsystems, then an appropriate Lyapunov-Krasovskii function is chosen to analyze the exponential stability of the error system. The designed synchronization controller can synchronize the two chaotic systems in a short time, meanwhile the relations among the sampling period bound, the synchronization time and the data missing rate are discussed. Simulation results show that the useful signal can be masked and recovered effectively based on the chaotic masking technique.Finally, a conclusion is given and the further research area is also proposed.