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.