New model reference adaptive control with input constraints

A new scheme of adaptive control is proposed for a class of linear time-invariant (LTI) dynamical systems, especially in aerospace, with matched parametric uncertainties and input constraints. Based on a typical and conventional direct model reference adaptive control scheme, various modifications have been employed to achieve the goal. “Composite model reference adaptive control” of higher performance is seamlessly combined with “positive μ-mod”, which consequently results in a smooth tracking trajectory despite of the input constraints. In addition, bounded-gain forgetting is utilized to facilitate faster convergence of parameter estimates. The stability of the closed-loop system can be guaranteed by using Lyapunov theory. The merits and effectiveness of the proposed method are illustrated by a numerical example of the longitudinal dynamical systems of a fixed-wing airplane.