IJCAS

This paper presents a novel robust H∞ model reference adaptive tracker (MRAT) for a class of nonlinear systems with input nonlinearities, uncertainties, and mismatched disturbances. Since the bounds of input nonlinearities and uncertainties are unknown, a new adaptive controller is proposed to solve these problems. Because the proposed adaptive laws are with convergence, the adaptive gains estimated can avoid overestimation. Furthermore, the sliding mode control (SMC) is implemented integrated with a smooth function, then the undesirable chattering phenomenon is reduced. Finally, the proposed tracking controller can process the undesirable effects of external disturbances and promote the tracking performance even subjected to the unknown input nonlinearity. The numerical simulation results demonstrate the robustness and validity of the proposed tracking controller.

Keywords: Adaptive control, input nonlinearity, robust tracker, sliding mode control.