Eye on the Sky: An Upward-Looking Monocular Teach-and-Repeat System for Indoor Environments

Visual Teach and Repeat (VT&R) allows a robotic vehicle to navigate autonomously along a network of paths in the presence of illumination and scene changes. Traditionally, the system uses a stereo camera as the primary sensor for triangulating visual landmarks and often operates in highly textured outdoor environments. In this paper, we modify the VT&R system to use a monocular pipeline under the same framework, but also target indoor operation as a demonstration of a low-cost VT&R solution for warehouse logistics in a visually difficult environment. Unlike previous monocular VT&R solutions, we make no assumptions about the nature of the scene (e.g., local ground planarity). This allows the system to be readily deployable on more vehicles in a wider range of environments. To test the system, and motivated by a warehouse navigation application, an upward pointing camera is mounted on a Clearpath Husky ground vehicle. We demonstrate the vehicle is able to navigate with a 99.6% autonomy rate using such a system during 1.1 kilometers of driving, with an average scene depth that varies from 8-16 meters. The cross-track deviation from the taught path is less than 0.5 meters over 90% of the path, reaching a maximum of 0.85 meters and an average of 0.26 meters.