| Chaos is a special moving form of nonlinear dynamics system, whose trajectory of the orbits in the phase plane is very complex, pseudorandom, and can be observed in fairly simple dynamical systems. Chaotic signal has the properties of pergodic, nonperiodic, continuous broadband power spectra, and noise like etc. These properties coincide with the requirements for signals applied in security communication systems. And the fractional -order chaotic system is very useful for security communication because it is a new chaotic system for its order is adjustable and the actual system usually is differential form. This dissertation has researched on the synchronization control of chaotic system and the fractional-order chaotic system and its application in secure communication. The detail is clarified as follows:(1)A method of uncertain Van der Pol chaos synchronization via fuzzy control is proposed.We directly construct a fuzzy controller based on the theory of fuzzy control for the synchronization of uncertain master-slave Van der Pol chaos system. Two couple of simulation results show the effectiveness of the proposed method. But in order to further show the effectiveness of the method, in the same conditions, an approach of the synchronization of uncertain master-slave Van der Pol chaotic system using feedback control is proposed, which compares in steady-state error and the time of synchronization with the proposed method. The results show the effectiveness of the proposed method too.(2)Chen chaos synchronization via sliding mode controller and its application is proposed.The synchronization problem of two identical Chen chaotic systems is studied and the design of a sliding mode controller is presented. Firstly, we directly make master-slave Chen chaotic system satisfy stability in the Lyapunov sense. Secondly, we propose a sliding mode controller to synchronize the Chen chaotic systems. Simulation results show the effectiveness of the proposed method. Moreover the information signal can be recovered undistorted when this method is applied to secure communication.(3)Fractional-order chen chaos synchronization via nonlinear feedback controller and its application is proposed.Chaotic synchronization of two identical Chen systems with the same fractional order is studied by nonlinear control method. The sufficient conditions for achieving synchronization between these two systems are derived based on the Laplace transformation theory. Numerical simulations show the effectiveness and feasibility of the theoretical analysis. Moreover the information signal can be recovered undistorted when this method is applied to secure communication. |
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