New composite MRAC with modification for fixed-wing UAV

In this paper, we present a new model reference adaptive control (MRAC) for flight control of fixed-wing unmanned aerial vehicle (UAV) with uncertainties and disturbance. The beginning of new algorithm design is combining direct MRAC with indirect adaptive control, which is called composite MRAC (CMRAC). In the aspect of direct MRAC, we substitute a Luenberger-like reference model for a typical one, namely adding an error feedback term. In the indirect part, we use a reverse filter to filter the system input. This kind of combination results in smooth transient performance and extremely small tracking error. In addition, we design adaptive laws with σ-modification to improve robustness in the presence of disturbances. Stability of the closed-loop system is formally proven by using Lyapunov theory. The effectiveness of the proposed algorithm is also illustrated through some simulations about the longitudinal dynamics of UAV.