A Practical Design Approach for Complex Path Tracking Control of a Tailless Fixed-Wing Unmanned Aerial Vehicle With a Single Pair of Elevons

This article presents a practical design approach for complex path tracking control of a tailless fixed-wing unmanned aerial vehicle (UAV) with a single pair of elevons, which is considered to be one of the most challenging UAVs to control. The proposed approach provides a well-balanced design that considers both the kinematics and dynamics of the UAV. A sum-of-squares (SOS) design framework is employed to achieve the complex path tracking control of the tailless UAV. By introducing \mathcal {S}-procedure relaxations, more relaxed SOS conditions are newly derived to design a controller that satisfies three design requirements: 1) a sufficient decay rate of the bank angle error, 2) a real actuator constraint, and 3) a smaller L_{2} gain with respect to the rotational motion dynamics. Instead of finding a unique and fully optimized feedback gain that satisfies the three SOS design requirements, the design approach finds a selectable region of semioptimized feedback gains that satisfy the SOS inequality constraints. The design policy is suitable for practical use as it allows for adjusting feedback gains within the specific selectable region during actual experiments to handle flight performance degradation caused by unmodeled characteristics. Finally, flight experiment results demonstrate the utility of the proposed design approach.