Global practical tracking control for high-order nonlinear uncertain systems

The problem of practical tracking control is studied for high-order nonlinear uncertain systems, which has been investigated under the assumption that the unmeasurable states in the nonlinear vector field can only grow linearly and the nonlinear systems are low-order. This paper studies the problem that the systems are high-order which have the higher-order growth of unmeasurable states. By means of designing a proper controller and utilizing the homogeneous domination approach, we achieve the objective that the static tracking error arbitrarily small and the systems have nice properties such as robustness to disturbances and universal property to reverence signals. Further, the results are extended to several proper conditions.