There's No Place Like Home: Visual Teach and Repeat for Emergency Return of Multirotor UAVs During GPS Failure

Abstract

Redundant navigation systems are critical for safe operation of UAVs in high-risk environments. Since most commercial UAVs almost wholly rely on GPS, jamming, interference, and multi-pathing are real concerns that usually limit their operations to low-risk environments and visual line-of-sight. This letter presents a vision-based route-following system for the autonomous, safe return of UAVs under primary navigation failure such as GPS jamming. Using a Visual Teach and Repeat framework to build a visual map of the environment during an outbound flight, we show the autonomous return of the UAV by visually localizing the live view to this map when a simulated GPS failure occurs, controlling the vehicle to follow the safe outbound path back to the launch point. Using gimbal-stabilized stereo vision and inertial sensing alone, without reliance on external infrastructure, Visual Odometry and localization are achieved at altitudes of 5-25 m and flight speeds up to 55 km/h. We examine the performance of the visual localization algorithm under a variety of conditions and also demonstrate closed-loop autonomy along a complicated 450 m path.