Robust adaptive control of nonlinear systems with asymmetric non-smooth saturation

In this paper, the robust adaptive control is proposed for a class of parametric uncertain nonlinear system with asymmetric non-smooth input saturation. By introducing a well-defined smooth function, a robust adaptive control algorithms are developed to deal with the problem of asymmetric non-smooth saturation. Unlike most of the existing control schemes for the uncertain nonlinear system, which requires an assumption that the control gain is an unknown constant, the developed controller only needs that the control gain is a bounded and unknown time-varying function. In this work, the robust adaptive controller can guarantee global uniform boundedness of the closed-loop system signals as rigorously proved by Lyapunov analysis. A simulation results is presented to illustrate the effectiveness of the proposed adaptive control technique.