Constrained robust adaptive control design for fixed wing uav under parameter uncertainties and external disturbances

This paper presents a Robust Model Reference Adaptive Control (RMRAC) for fixed wing UAV trajectory tracking. Trajectory tracking of Fixed Wing UAV(FWUAV) is extremely complicated due to the under actuated and coupled dynamics with unknown aerodynamic coefficients. The proposed adaptive control technique consists of two loops to address the issue of under actuation: an inner loop regulates attitude, while an outer loop generates reference trajectories for the inner loop. First, the Newton-Euler technique is used to establish FWUAV dynamic models. To simplify complexity, the dynamic models are decoupled. There are six second order single-input multiple-output (SIMO) systems in the decoupled dynamics. Second, a conventional Model Reference Adaptive Control (MRAC) is designed. Nevertheless, in the face of unparalleled unpredictability, this controller experiences instability. Third, to avoid parameter drift in off-nominal situations, a Robust Model Reference Adaptive Control (RMRAC) was proposed. To solve the robustness issue, the paper also suggests robustness modification strategies. For the stability analysis, Lyapunov’s direct technique is employed. Lastly, using extensive simulation studies, the RMRAC is tested for parametric uncertainty and external disturbance, demonstrating the efficacy of the proposed controller in tracking the intended trajectory.