Synchronization Control Of Delayed Uncertain Chaotic Systems And Its Applications In Secure Communication

To improve the secret performance, chaotic systems are usually used in the secure communication to fully utilize their inherent characteristics such as random, the wide frequency chart, initial sensitivity, and so on. Chaotic synchronization is one of key technologies for achieveing chaotic secure communication. To obtain the chaotic systems with more complex dynamic character and to design the chaotic synchronization controller with high robust performance is the hot topic in the development of chaotic secure communication. At the same time, the state time delay and the uncertainty are two inevitable factors of the actual chaotic systems. Thus, the state time delay and the uncertainty are considered in the chacotic synchronization design which is more suitable for the practical application. This thesis focuses on the design of chaotic synchronization control of the various time delayed uncertain chaotic systems and its application in the secure communication. The main works and innovative points of this paper are as follows:First of all, the constitution means and judgement principles of the delayed chaotic systems have been studied. The delayed Lorenz chaotic systems, the delayed triangular chaotic systems, the delayed chaotic neural networks and a new class of time delay chaotic systems have been constructed and the characters of these constructed chaotic systems have been analysed and judged.Then, the active synchronization and anti-synchronization controllers of the different delayed uncertain Lorenz chaotic systems have been designed and the simulation results have been presented. The synchronization controllers of the delayed uncertain Lorenz chaotic systmes with disturbance have been developed. One-dimension synchronous controller has been designed via using the adaptive sliding mode control based on radial basis fuction (RBF) neural ntwork. Furthermore, the robust constrained synchronous controller has been proposed by using the nonlinear disturbance observer based on RBF neural network. The synchronous performance of the developed synchronization control schemes can be guaranteed.Subsequently, one-dimension adaptive sliding-mode controller has been developed to realize the synchronization of the uncertain parameter triangle chaotic systems. On the based of the study, the synchronous control of the uncertain parameter triangle chaotic systems with the uncertain configuration has been further studied. The synchronization of the chaotic systems has been achieved by designing the disturbance observer based on the neural network and the backstepping adaptive control technique. The simulation results have demonstrated that the proposed synchronization control is effective.Following, the robust adaptive neural network synchronous control scheme has been proposed for the identical time-varying delay uncertain recurrent chaotic neural networks. Two various synchronous controllers have been developed for the uncertain time-varying delay neural networks with noise. One controller is the H∞synchronous controller and the other controller is the robust controller based on the disturbance observer. The simulation results have demonstrated that the proposed synchronization control schemes are effective and correct.Finally, the synchronous control of a class of delay uncertain chaotic systems with parameter perturbations and its application in secure communication have been studied based on disturbance observer. On the other hand, the secure communication of the Lorenz chaotic synchronization under the disturbance has been achieved by using the chaotic modulation technique. At the same time, the original time-varying signals have been considered in the secure communication. In general, the time-varying original signals can be only recovered under the low frequency. Howerver, the developed Lorenz chaotic synchronization can overcome the problem. Furthermore, the secure communication of the H∞synchronization for the identical time-varying delay chaotic neural networks has been proposed by using the techniques of chaotic masking and chaotic modulation. The developed secure communication technology can recover the hidden multiplex original signals. At the same time, the synchronization circuit of the delayed Lorenz chaotic systems is designed and the effective values of circuit components are deduced. The simulation results based on the designed circuit are presented using the Electronic Workbench simulation software. The simuation results also demonstrate that the image can be transmitted securely by using the chaotic masking technique and can be recovered effectively via the developed synchronization circuit of the delayed Lorenz chaotic system.