I. Introduction
Pecora and Carroll, [1], have proposed a master-slave strategy for chaos synchronization, although the characteristic of chaotic systems would conflict the synchronization design. The widespread methods in this context are the adaptive control [2], the sliding mode control [3], the robust interval observer [4], the gravitational search algorithm filter [5], etc. Besides, applying the state observer approach for chaos synchronization seems to be a challenging task. The authors in [6] proved that estimating the chaotic systems via nonlinear state observer techniques is achievable. Actually, the chaotic transmitter is considered as a nonlinear dynamical systems, while its receiver is contemplated as an observer of the driving system, see for instance [7].