Abstract
We investigate the global robust tracking problem via output feedback for a class of cascade nonlinear systems with dynamic uncertainties and non-vanishing disturbances. It does not require a priori knowledge of the sign of the high-frequency gain. A recursive design scheme is presented using the ideas of pseudosign function, Nussbaum-type gain technique and the deadzone method. It is shown that under some conditions, the tracking error can be guaranteed asymptotic to the interval [−ε, ε]⊂ℝ with arbitrary prescribed ε>0 after a finite time, while keeping all signals of the resulting closed-loop systems bounded. The simulation results demonstrate the effectiveness of the proposed algorithm.
Acknowledgements
This work is supported by the National Natural Science Foundation of China (61304008, 61273091, 61273123, 61203013), the Natural Science Foundation of Shandong Province of China (ZR2013FQ033, ZR2011FM033), the Outstanding Middle-age and Young Scientist Award Foundation of Shandong Province (BS2011DX012) and the Doctor Research Foundation of Shandong Jianzhu University(XNBS1272).