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 increasingly attentions. However, control inputs missing and random varying sampling intervals often occur in real sampled-data control systems, which will seriously affect system performance or even destroy the stability of systems. Therefore, the thesis mainly studies the sampled synchronize control issue in chaotic secure communication systems with control inputs missing and random varying sampling intervals. The main contents of the thesis are as below:Firstly, in the thesis, a synchronization problem is investigated for the chaotic systems with control inputs missing in the condition of stochastically-varying sampling intervals. The hold-input strategy is used to transfer the missing data as input delays. In order to analyze the stability of systems, the error system is converted into error system with input delay by using input delay method. The gain of the designed controller can be calculated by linear matrix inequalities (LMIs) approach. Simulation results illustrate the effectiveness of the designed controller which can be well applied to the chaotic secure communication systems.Secondly, for the random sampling 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 a stable subsystem and an unstable subsystem. Then the stability analysis is given based on average dwell time method. Meanwhile, the relation between data missing rate and convergence rate are discussed. The simulation results show that the synchronization time of two Lorenz systems becomes shorter if data missing rate is smaller, and the designed control method can be applied to the chaotic secure communication.Thirdly, considering the directed complex network system with control inputs missing problems, the hold-input strategy is used to design sampled data synchronization controller for all nodes. And the synchronization conditions are obtained. In addition, a directed network with 10 nodes is taken in simulation. By analyzing the situation that all nodes are without packet loss, some nodes have packet loss at the same time and some nodes have packet loss at different time, we can get that the theoretical results derived here are proved to be effective. Furthermore, simulation results also 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.