Global Adaptive Practical Output Tracking Control for a Class of Genuinely Nonlinear Uncertain Systems: Adding an Universal Power Integrator Approach

In this paper, the output tracking problem for a large class of uncertain nonlinear systems with arbitrary integrator powers and nonlinearly parameterized unknown dynamics is addressed by employing an innovative tool called adding an universal power integrator (AUPI). By virtue of the AUPI methodology, flexible degrees of homogeneous are incorporated to mask rich diversities in integrator powers rather than simply positive odd integers involved in previous works. Moreover, a universal gain is adaptively updated according to the tracking error, which can converge into an arbitrarily small region including the origin, and thereby contributing to bounded but large enough controller gain and prescribed tracking accuracy. Numerical examples demonstrate the effectiveness of the proposed AUPI-based adaptive tracking control scheme.