Coordinated Aerial Exploration of Subterranean Voids

Abstract

Subterranean exploration has been thrust into the spotlight by the recent DARPA Subterranean Challenge. Teams are tasked with developing a multi-agent system that can rapidly navigate through unknown underground environments while sending back maps and other semantic information. A system with such capabilities has a wide variety of applications from surveying and mapping mines to search and rescue operations. Aerial platforms in particular have the ability to fly fast and discover large parts of an environment despite their lower operational endurance. They can also change altitude at will to explore narrow nooks in spaces that are otherwise difficult to access. The work done in this thesis aims to leverage these abilities to build a resilient autonomy pipeline that enables multiple drones to coordinate an underground exploration mission with the click of a button. Towards that end, we propose an integrated exploration and coordination pipeline that is designed to generalize across a variety of subterranean environments. An ensemble of planners has been built in to tackle a large set of operating conditions ensuring the robot is never still for too long. Coordination map sharing enables the aerial platforms to minimize the overlap in explored volumes between them and other robots on the team. An extensive set of field experiments show that the approach works well in subterranean spaces such as caves, mines and urban infrastructure. We conclude with a discussion on further work planned for improving the system in the future.