|Robust Adaptive Backstepping Control for an Uncertain Nonlinear System with Input Constraint based on Lyapunov Redesign
Fang Wang*, Qin Zou, and Qun Zong
International Journal of Control, Automation, and Systems, vol. 15, no. 1, pp.212-225, 2017
Abstract : "This paper presents the control problem for a class of n-order semi-strict nonlinear system subjects to
unknown parameters, uncertainty, and input constraint. The controller is designed via combining backstepping
control and Lyapunov redesign. Firstly, based on the Lyapunov function, a composite adaptive law is constructed
to estimate the unknown parameters. To sequel, a robust term is designed to handle the matched and unmatched
uncertainties on the basis of Lyapunov redesign technique. The “explosion of terms” problem that inherent in
backstepping control is avoided by the robust second-order filters. Thirdly, an auxiliary signal provided by the
auxiliary system is employed to handle the influence of the input constraint. It is proved that the closed-loop
system is stable in a Lyapunov framework theory and the semi-global uniformly ultimate boundedness of all signals
is achieved. Finally, numerical simulations are carried out to evaluate the performance of the proposed control
strategy. Numerical example and the application of the hypersonic vehicle (HSV) tracking control are simulated to
demonstrate the effectiveness of the proposed control scheme."
Keyword : Backstepping control, input constraint, Lyapunov redesign technique, nonlinear system, matched and unmatched uncertainty, unknown Parameter.