An infrared vision system for UAV close formation flight

Close formation flight can extend aircraft range and persistence through utilisation of a wingman's wake vortices or aerial refueling. Implementing these capabilities autonomously with unmanned aerial vehicles requires reliable relative state estimation with higher accuracy than GPS alone can provide. To address this, we propose an infrared marker and camera system to aid onboard GPS and inertial sensor measurements. The result is a highly accurate and reliable estimate of a lead aircraft, with respect to a follower. Ground based experiments have uncovered important nonlinear relationships between marker sensitivity and position in the camera frame as well as the expansion of the band-pass wavelength near the edge of the frame. Formation flight tests have demonstrated real-time marker detection and extraction in a variety of lighting conditions, at ranges in excess of 40m and on embedded hardware.