Stable Adaptation in the Presence of Actuator Constraints with Flight Control Applications

Abstract

reference adaptive control framework is developed that provides stable adaptation in the presence of multi-input constraints. ThedesignisLyapunovbasedandensuresglobalasymptotic tracking foropen-loopstable systems. For unstable systemsan estimate for the domain of attractionis derivedbasedonthe saturation magnitudes ofactuators and system parameters. The theoretical results are verified using linear roll/yaw dynamics of an F-16 aircraft, in which benefits of the developed methodology are demonstrated in the presence of aerodynamic uncertainties and control failures. I. Introduction I N THIS paper, we present a direct model reference adaptive control design method for multi-input systems in the presence of control magnitude constraints. The design of such methods has attracted a large amount of research effort over the past years [1–8]. The first attempt to modify an adaptive control scheme in the presence of saturation was proposed by Monopoli in [9] but without any formal proof of stability. In [3], a formal proof was given for the same idea, but it was limited to single-input systems. In [10], the results of [3] were extended to the class of multi-input systems, assuming an ellipsoid-based saturation function, as it is shown in Fig. 1. Because the actuator limits were artificially reduced, this type of approach introduced extra conservatism into the design. Here, we extend the result reported in [10] and prove closed-loop system stability in the presence of rectangular saturation function