Adaptive synchronization of chaotic systems via state or output feedback control

This letter addresses the problem of robust adaptive control for synchroniz ation of continuous-time coupled chaotic systems, which may be subjected to disturbances. A general model is studied via two different approaches, usi ng either state feedback or measured output feedback controls. Adaptive con trollers are designed, in which a sliding mode structure is employed to inc rease the robustness of the closed-loop systems. When only output variables are measurable for synchronization, the adaptive controllers are designed by incorporating with a filter and using the so-called sigma -modification technique. Several numerical examples are presented to show the effectivene ss of the proposed chaos synchronization methods.