Adaptive feedback synchronization of Lü system

This letter further improves and extends the works of Chen and Lü [Chaos, Solitons & Fractals 14 (2002) 643] and Wang et al. [Phys. Lett. A 312 (2003) 34]. In detail, the linear feedback synchronization and adaptive feedback synchronization for Lü system are discussed. And the lower bound of the feedback gain in linear feedback synchronization is presented. The adaptive feedback synchronization with only one controller is designed, which improves the proof in the work by Wang et al. The adaptive synchronization with two controllers for completely uncertain Lü system is also discussed, which extends the work of Chen and Lü. Also, numerical simulations show the effectiveness of these methods.