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

TL;DR

This paper introduces a vision-based system enabling multirotor UAVs to autonomously return to their launch point during GPS failure, using visual Teach & Repeat for reliable navigation without external infrastructure.

Contribution

It presents a novel visual Teach & Repeat approach for UAV emergency return, operating solely on stereo vision without external signals or inertial sensors.

Findings

Successful autonomous return at altitudes of 5-25 m

Visual localisation effective at speeds up to 55 km/h

Demonstrated closed-loop navigation on a 450 m path

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 paper 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 & Repeat framework to build a visual map of the environment during an outbound flight, we show the autonomous return of the UAV by visually localising 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-stabilised stereo vision alone, without reliance on external infrastructure or inertial sensing, visual odometry and localisation are achieved at altitudes of 5-25 m and flight speeds up to 55 km/h. We examine the performance of the visual localisation algorithm under a variety of conditions and also demonstrate closed-loop autonomy along a complicated 450 m path.