Editorial: Special Issue on Advancements and Lessons Learned during Phases I and II of the DARPA Subterranean Challenge

Abstract

Complex underground environments such as tunnels, underground urban settings, and natural caves present significant challenges for first responders in the event of an emergency. Each of these subdomains has unique hazards while sharing some common elements. Apart from challenging terrain features and aspects such as smoke and dust, communications in these environments are often severely degraded as well. Motivated by these difficulties, the Defense Advanced Research Projects Agency (DARPA) Subterranean Challenge (SubT) was set up to drive the global robotics community to develop novel approaches to rapidly map, navigate, and search underground environments under time pressure. The DARPA SubT,1 conducted from April 2019 to September 2021, was organized as two competition tracks. In the systems track, teams developed and demonstrated physical systems and competed live in real subterranean environments representative of the three subdomains. In the virtual track, teams developed software and algorithms using virtual models of systems and environments to compete in simulation-based events representative of the three subdomains. Phase I and Phase II of the systems track of this challenge consisted of the following events: 1. SubT Integration Exercise (STIX) at the Edgar Experimental Mine in Idaho Springs, Colorado, USA, in April 2019. 2. Tunnel Circuit event at the National Institute for Occupational Safety and Health (NIOSH) mine in Pittsburgh, Pennsylvania, USA, in August 2019. 3. Urban Circuit event at the Satsop Nuclear power plant in Elma, Washington, USA, in February 2020. The Cave Circuit event scheduled for August 2020 was canceled by DARPA due to the COVID-19 pandemic. As a result, a number of the competing teams held their local Cave events to evaluate their system performance in natural cave environments. In each of these events, the task was to deploy a fleet of robots into the subterranean course to locate and identify a set of predefined artifacts within the 60-minute run time. These artifacts included cell phones, backpacks, power drills, fire extinguishers, survivors (thermal mannequins), air vents, rooms with high carbon dioxide concentration, climbing rope, and helmets. A point was scored for each correctly identified artifact located within a 5-meter accuracy. Only one human supervisor was allowed to control and communicate with the robots once the run started. A pit crew of 10 personnel was allowed to set up the robots in the staging area outside the course entrance in the 30-minute period immediately prior to the run.