“…This shows that the uncertainties in (1), represented by f (x p ), can not be parameterized. The adaptive tracking control of uncertain nonlinear systems has been attracted much attention during the past decades (see, for instance, [1], [2], [3], [4] and the references therein). However, most researches of the adaptive tracking control devoted to the systems with linearly parameterized uncertainties, that is, the uncertainties can be represented by functions of the form f (x p ) = θ T ψ(x p ), where ψ(x p ) is a known function vector and θ is an unknown parameter vector.…”