Adaptive output feedback control of uncertain nonlinear systems with input saturation

Abstract

AbstractThis article concerns with the tracking control problem for a class of control‐affine nonlinear systems subject to input saturation, parametric uncertainties and unmodeled uncertainties. The proposed scheme consists of a nested‐saturation‐function‐based controller integrated with feedforward model compensation. A saturated linear extended state observer (SLESO) and parameter adaptation law are constructed to compensate for the unmodeled uncertainties and parametric uncertainties, respectively. By using these mechanisms, the steady‐state tracking performance can be guaranteed through uncertainty compensation. Additionally, the issue of conservativeness in the input saturation problem is effectively addressed through online‐updating the available unsaturated region, which improves transient performance. The proposed scheme results in asymptotic stability when unmodeled uncertainties are constants and ultimate boundedness when unmodeled uncertainties are time‐varying. Finally, simulation studies are presented to demonstrate the effectiveness of the proposed approach.