In this brief, an adaptive chaos control method is developed for stabilizin
g chaotic systems at their unknown equilibrium(s) using the invariant manif
old theory, The developed method overcomes the problem that the equilibrium
(s) of the chaotic systems are dependent on the unknown system parameters,
which makes direct application of the conventional adaptive control difficu
lt, Further development of the adaptive chaos control is undertaken for the
situation where the parameter estimates are only allowed to vary within a
bounded set due to the sensitivity of chaotic systems to parameter variatio
ns. A sufficient condition for convergence of system states and parameter e
stimates is obtained. The design method developed then is applied to stabil
izing the Lorenz chaotic system at an unknown equilibrium. Both mathematica
l and computational results have demonstrated the effectiveness of this met
hod.