Fractional-Order Control on PX4 Firmware: Open-Source Implementation for Fully actuated Hexarotors

This paper presents a robust control strategy for fully-actuated Hexa-rotor aerial vehicles, capable of rejecting external disturbances affecting both position and attitude dynamics. The proposed controller incorporates a fractional-order integral action in the position subsystem, and it is theoretically proven that the resulting closed-loop system ensures global exponential stability of the tracking error. The control design is validated through MATLAB simulations and software-in-the-loop (SITL) experiments using PX4, the most widely adopted open-source autopilot firmware. The SITL tests are conducted in a realistic 3D Gazebo environment. To assess its effectiveness, the proposed controller is benchmarked against four state-of-the-art strategies, including fractional-order and nonlinear approaches, under identical disturbance conditions. Results show that the proposed method achieves a favorable balance between tracking accuracy, robustness, and control effort, while requiring fewer tuning parameters than competing strategies. Additionally, the implementation is made openly available in PX4 to encourage reproducibility and future development in the field.