Research On Synchronization Control Methods For Time-delay Chaotic Systems

Time-delay chaotic systems are hyperchaotic systems with multiple positive Lyapunov exponents.Compared with non-delayed chaotic systems,their dynamic behavior is more complicated and has a vide range of applications.The synchronous control of time-delay chaotic systems is more widely used in many fields such as information processing,biomedicine and secure communications.High-efficiency and high-precision chaotic synchronization can be better applied in secure communication and biological engineering.Therefore,the performance requirements for synchronization control of time-delay chaotic systems are more stringent.At the same time,it is more challenging to investigate the synchronization control strategy of time-delay chaotic systems with uncertainties and time-varying delays.In this thesis,the time-delay chaotic system with uncertainty is taken as the research object.Adaptive fault toleranc e technology,H_?observer technology and global sliding mode control technology are applied respectively to realize synchronization control of the chaotic systems.The effectiveness of the designed controller is verified from two as pects:the theoretical derivation and numerical simulation.The specific research contents include:1. For the chaotic systems with uncertain parameters and nonlinear time delays,a robust adaptive fault-tolerant controller is designed.Without the need to know the exact fault information,the adaptive law is used to estimate the unknown parameters online,so that the synchronization error system quickly converge to zero in a finite time and the synchronization control of the nonlinear state-delayed chaotic system is realized.2. In the view of the problem of unmeasurable state in time-varying time-delay chaotic systems,an H_?observer and a state feedback controller with memory are designed to realize the synchronous control of a cla ss of chaotic systems with input and output time-delay.Compared with the existing literature,under the action of the controller designed in this thesis,the synchronization error system has faster synchronization speed and higher synchronization accuracy.3. For the synchronization control of time-delay chaotic systems with parameters uncertainty and Lipschitz nonlinearity,a global integral sliding mode controller based on composite nonlinear feedback is designed to realize the synchronization control of a class of chaotic systems with multiple time-varying delays.Compared with the existing literature,it can effectively shorten the synchronization time,meanwhile it can improve the synchronization accuracy and enhance the interference ability of the system.