Robust adaptive control for a class of perturbed strict feedback nonlinear systems

This paper presents a robust adaptive control approach for a class of perturbed strict feedback nonlinear systems with both completely unknown virtual control coefficients and parametric uncertainties. The proposed design method does not require a priori knowledge of the signs of the unknown virtual control coefficients. It is proved that the proposed robust adaptive scheme can guarantee the global uniform ultimate boundedness of the closed-loop system signals. Simulation studies are included to illustrate the effectiveness of the proposed approach.