Thermal-Inertial Odometry for Autonomous Flight Throughout the Night

Thermal cameras can enable autonomous flight at night without GPS. However, image-based navigation in the thermal infrared spectrum has been researched significantly less than in the visible spectrum. In this paper, we demonstrate closed-loop controlled outdoor flights at night on a quadrotor. Our state estimator can tightly couple inertial data with either thermal images at nighttime, or visual images at daytime. It is integrated in an autonomy framework for motion planning and control, which runs in real time on a standard embedded computer. We analyze thermal-inertial odometry performance extensively from sunset to sunrise, for various thermal non-uniformity levels, and compare it to visual-inertial odometry at daytime.