Observer-based adaptive variable structure control and synchronization of unknown chaotic systems

Most physical chaotic systems inherently contain nonlinearities which are commonly unknown to the system designer. Therefore, in modeling and analysis of such chaotic systems, one needs to handle unknown nonlinearities and/or uncertain parameters. This paper addresses two new adaptive output feedback controllers for a large class of chaotic systems with unknown dynamics in presence of external disturbances. As a generalization of the control problem, synchronization of two uncertain chaotic systems is also investigated. In order to verify the effectiveness of the proposed methods, the methods are applied to Liu chaotic system.