Flatness-based Control of a Gimballed Fixed-Wing UAS

This paper derives a differential flatness model for a fixed-wing unmanned aircraft system (UAS) together with a gimballed camera. The flat output is the 3D trajectory of the aircraft and the 3D trajectory of a ground target. An LQR controller is then derived so that the UAS follows the desired trajectory and the optical axis is aligned with the line-of-sight vector between the UAS and the target. A simple simulation study shows that the framework can be used to visually track and follow a ground target, maintaining the optical axis alignment to within 1.2 degrees.