Abstract
This article presents a modify adaptive combined synchronization for a class of different unknown fractional order chaotic systems. A combination of different states of the drive systems asymptotically synchronizes with the desired states of the response system. Hence, increases the complexity of the communication channel in secrete communications. The Lyapunov stability theory proves the asymptotic stability of the error system at the origin. The design of a suitable adaptive controller assures the target synchronization. This work provides parameters update laws that estimate the true values of unknown parameters. This paper also presents two numerical examples of unknown different fractional order chaotic systems and simulation results that validate the efficiency and performance of the proposed adaptive combined synchronization strategy. The presented adaptive combined synchronization strategy can be applied to multiple synchronization strategies. The paper suggests some future problems related to this work.