Font Size: a A A

Research On Synchronization Of Chaotic System And Its Application In Secure Communication

Posted on:2011-07-28Degree:DoctorType:Dissertation
Country:ChinaCandidate:L J ZhouFull Text:PDF
GTID:1118360305978228Subject:Oil and gas information and control engineering
Abstract/Summary:PDF Full Text Request
The phenomenon of chaotic is one of most important scientific discoverys and academic research hots of the twentieth century. The chaotic movement has characteristics of the extreme sensitivity to initial values, a high degree of randomness, and the certainty of nonlinear equations, so it has been widespread concern. Chaos synchronization, as an important research direction for chaos, has a great value and potential in Secure communications. Main contents of this article are as follows:Firstly, as for the unified chaotic system,the adaptive synchronization is studied when the parameter of drive system is unknown and the parameter of response system is adjustable. Based on Lyapunov stability theory and combining methods of driving and feedback, two new adaptive control methods for the synchronization are presented by employing multiple controllers and only a single controller. The analytical expression of synchronization controller and adaptive law of parameter are given. As for the synchronization of the unified chaotic system and Rossler system, based on a kind of tridiagonal structure, controllers are designed in accordance with direct construction method. The error system is transmated the tridiagonal structure. Because the nonlinear system of such structure is globally asymptotically stable, the error system is asymptotically stable at the origin. So the synchronization is realized.Secondly, as for generalized synchronization for chaotic systems with unknown parameters, an adaptive synchronization control method based on state observer is proposed. This method uses a nonlinear state observer with a controller to realize generalized synchronization and estimate the unknown parameters. Furthermore generalized synchronization velocity can be improved according to configuration of poles, without a limit of stability of linear part of the chaotic system. The unified system is taken for verification, and the results of the simulation indicated the efficiency of this method.Thirdly, as for the generalized synchronization for the Lorenz system, a new method of variable structure and multi-input is presented. The method uses exponential reaching law, and chooses the appropriate switching function. That ensures that the two components of the error vector rapidly tend to 0, and the movement of the third component becomes eventually sliding mode on the switching surface and quickly tends to 0 exponentially. Forthly, as for Choas Secure Communication, chaotic masking method is used to realize secure communications of the unified system. Then based on state observer method, hyperchaotic synchronization secure scheme is proposed. When hyperchaotic systems of receiver and sender reach synchronization, the original information signal is rescovered. Lorenz system is taken for verification.Lastly, based on an output linearization feedback control method, nonlinear partial of chaotic system is linearized, and synchronization of two chaotic systems is achieved by use of linear methods. According to the method, chaotic secure communication system is designed. The output signal is transmitted from one channel to, and the information signal through the modulation of the cover and hide is transmitted by an alternative route.
Keywords/Search Tags:chaos synchronization, unified chaotic system, state observer, sliding mode control, secure communication
PDF Full Text Request
Related items