Abstract
This paper concerns the problem of online estimation of unknown disturbances of multi-input unknown chaotic systems and designs a disturbance rejection controller according to the estimation information. A model reference adaptive control technique is used in which the controller is designed such that the states of the chaotic system follow the states of the prescribed reference model. Only the dimensions of the chaotic systems are required to be known. Based on Lyapunov's stability theory, adaptive control laws are synthesized. Illustrative example with numerical simulations is studied. The simulation results show that our control method works very well in chaos control.