Research On Synchronization Control Methods For Uncertain Chaotic Systems

In recent years,in the field of nonlinear,chaos synchronization has become a hot topic for researchers.Due to the extremely sensitive of chaotic systems to initial conditions and parameters as well as random,the chaotic synchronization has been widely used in the fields such as secure communications,biological engineering,information processing.The realization of the chaos synchronization brings some guarantees for the applies,therefore,the performance of the chaotic synchronization control has more stringent requirements.At the same time,the control for the uncertainty of chaotic systems is a big problem in the study of chaotic synchronization.With uncertain chaotic system as the research object,the sliding mode variable structure control,adaptive control and robust fault-tolerant control method are provided to study chaos synchronization.The correctness of the designed control method are proved from two aspects of theoretical derivation and numerical simulation.The specific research contents include:1.The research status of chaos theory and chaotic synchronization control are summarized,the development status,control idea and design method of the adaptive control,sliding mode variable structure control and robust fault-tolerant control are introduced in detail.2.For the two uncertain chaotic systems with unknown parameters and nonlinear input,an adaptive sliding mode control law is designed to make the synchronization error converge to zero in finite time and realize the synchronization between two different chaotic systems.Compared with traditional methods,a terminal sliding mode surface is proposed with faster convergence speed in this thesis,and an adaptive law is designed to estimate the unknown parameters in the system.The unknown parameters,nonlinear input,uncertainty and external disturbance and many other factors are taken into account so that the controller more conform with the engineering application.3.In view of the chattering problem in sliding model variable structure control,a finite time adaptive chatter free sliding mode control strategy is put forward to achieve synchronization control problem for a class of uncertain chaos systems.In this method,a dynamic sliding mode surface with finite time convergence is designed,the discontinuous sign function is transferred to the first derivative of the control law,the chattering is suppressed effectively.4.For a class of chaotic systems with actuator failures,nonlinear uncertainty as well as the disturbances,a robust adaptive fault-tolerant controller is designed to achieve the master-slave fault-tolerant synchronization.In the article,the accurate fault information and the upper bound of the disturbance are unknown,according to the adaptive law to estimate the unknown online,no matter whether actuator failure,master-slave chaotic systems can achieve synchronization effectively.