Adaptive output tracking for high-order uncertain nonlinear systems

The problem of output tracking has been further investigated for a class of high-order nonlinear systems with uncertain control coefficients and unmeasurable zero dynamics. Compared with the existing works, restriction on zero dynamics is further relaxed. The design procedures of the continuous adaptive tracking controller are provided by flexibly incorporating the method of adding a power integrator with the related adaptive technique and the idea of changing supply functions. Finally, a numerical example is given to demonstrate the effectiveness of the control scheme.