Synchronization and secure communication of uncertain chaotic systems based on full-order and reduced-order output-affine observers

This paper deals with the problems of chaos synchronization and secure communication for a class of uncertain chaotic systems. The uncertain chaotic systems under consideration are subject to modeling uncertainties and depend affinely on a set of measurable system outputs. Two types of observer are proposed to achieve chaos synchronization and secure communication. First, a full-order output-affine observer is proposed to simultaneously estimate the system states and the message signals. Second, a reduced-order output-affine observer is proposed to simultaneously estimate the unmeasured system states and the message signals. A numerical example is given for a chaotic system to show the design procedure and the effectiveness of the proposed observers. The simulation results indicate that the proposed observers work well.