Nonlinear Feedback Linearization Control and Region of Attraction Analysis for a Fixed-Wing UAV

This paper presents the design of a nonlinear Multi-Input Multi-Output (MIMO) Feedback Linearization Controller (FLC) for the longitudinal dynamics of a fixed-wing UAV. The proposed approach employs dynamic extension to achieve Feedback Linearization in a fourth-order longitudinal model, offering a more compact alternative to existing high-order formulations. The controller ensures the accurate tracking of predefined airspeed and flight path angle references, that is, the control of the magnitude and direction of the velocity vector using engine thrust and pitch moment as control inputs. Additionally, this study determines the region of attraction in which the controller design remains well-defined. This analysis provides critical insights for selecting feasible airspeed and flight path angle references, helping to prevent conditions that can lead to instability or undesirable behaviors, such as the need for negative thrust. Numerical simulations validate the effectiveness of the proposed method in handling the aircraft’s nonlinear dynamics and maintaining stable flight performance.