Australian robots achieve historic underground mine inspection

Rajant Corporation, provider of Kinetic Mesh wireless networks, and its technology partners Australian Droid and Robot (ADR) and PBE Group have completed the deepest remote underground mine inspection in history. Using 10 ADR Explora XL unmanned robots from Queensland technology company ADR and a wireless below-ground communication network, a mobile infrastructure depth of 1.7 km was achieved to enable the re-establishment of operations at a collapsed limestone mine and restore jobs.

A significant, unexpected mine collapse occurred in August 2021 causing an expulsion of air carrying dirt and rocks that flew out of all portals and ventilation raises. The air was estimated to be moving around 190 kph. It was determined that this collapse was caused by the failure of very old pillars (40 to 70 years old) thus creating a substantive surface subsidence. The surface subsidence measured approximately 240 m across and over 30 m deep. No-one was injured in the incident, as the mine had been evacuated well prior to the incident. Working with the Mining Safety and Health Administration (MSHA), the operator and MSHA determined no one should enter the mine until some type of unmanned survey could be conducted to assess the conditions of the mine safely. The solution to achieve this came through the collaboration of ADR, PBE and Rajant.

“Prior to the collapse, the mine had a two-way radio system running over a leaky feeder,” said Rajant Sales Director Todd Rigby. “The leaky feeder was not functional following the collapse, nor did it have sufficient bandwidth to support unmanned robots or drones. Rajant BreadCrumbs were installed by Rajant’s channel partner PBE mostly at the surface of the mine to provide a reliable high-bandwidth link from the portal to an emergency operations centre overseeing the remote surveying done by ADR and its fleet of all-terrain ground robots equipped with BreadCrumbs.

“The robots initially dragged three network infrastructure points into the mine and then staggered along various routes up to 1.7 km deep. During the longest mission, the robots were transmitting 80 Mbps, and included high-definition video and lidar to create a virtual 3D model of the mine.”

“ADR keeps a small fleet of robots ready to go for emergencies, but this was going to require more units with different sensors and capability,” said Dr Joe Cronin, Operations Manager and one of the founders of Australian Droid & Robot. “We quickly built more robots and undertook a thorough testing regime to imitate the conditions and distances we would experience in the US. We had teams all over Brisbane, and at one stage, we had robots strung across more than one suburb, controlled from a central location. The robots were shipped to the US less than a month later and were accompanied by Andre Preller, Head Electronics Engineer, and Callum MacDermid, Senior Robotics Engineer.

“After a day’s testing on the surface, the robots entered the mine, each robot relaying the communications signal to the next, creating a high-bandwidth, daisy-chain network into the mine. A week later, the team had acquired enough data for the mining team to be able to restart operations.”

“Before the collapse, PBE was the mines communications infrastructure provider. When we learned about the need for unmanned inspection after the collapse, we focused on finding the best solution for fast, flexible deployment and high performance,” added Rob Koch, Director of Technology, PBE Group. “The mine needed a high-throughput, flexible data network to support a broad and changing set of inspection deployments. The Rajant mesh technology was the clear choice for this need.

“In execution, the challenge was to design network elements deployed into the mine by the robots themselves. We moved quickly to source the best antenna technology for the robots and backhaul nodes. Then we went onsite to build the robot deployable nodes and surface network to move data to the inspection operation centre. The network and antenna elements provided plenty of time to facilitate the inspection event. We are glad the mine chose PBE on this groundbreaking project to safely bring the mine back into production using the best technology available.”