Australian engineers have sent a robot where no other has gone before, completing the deepest remote underground mine inspection in history.
Brisbane-based Australian Droid & Robot (ADR) used a fleet of robots to reach 1.7 kilometres into an underground limestone mine in the south-eastern United States.
The robots conducted a comprehensive laser scan and visual inspection of the mine geometry, following a collapse.
Callum Macdermid, ADR’s Senior Robotics Engineer for Technical Information, told create that the robots they deployed were the result of five years of iterative development.
“All of our technology is designed with the philosophy of ‘safety by separation’ — it guides our work and solidifies our vision,” he said.
“We have a range of robotic platforms which we’ve developed in-house called the Explorer XL. Using the systems of our communications partner, Rajant Corporation, we were able to daisy chain or bunny hop the robots down into the mine.”
The remote inspection robots were developed with Rajant Corporation’s Kinetic Mesh industrial wireless networking radio technology to create long-distance, low latency networks in real time. After a day’s testing on the surface, the robots entered the mine, with each robot relaying the communications signal to the next, creating a high bandwidth network into the mine.
“We had a base station, and oversaw the operation using our own graphical user interface (GUI) to control the robots that can run on any generic Windows or Linux laptop,” Macdermid added.
“It has a really intuitive design and we can just plug in an Xbox controller and operate the robots from a big television. We had a live view of the robots, it almost felt like we were playing a video game.”
After a week of remote operations underground, enough data was acquired for the mining team to begin to restart operations.
Under the LIDAR
The robot deployed was designed to be a universal platform that can host any payload, including gas sensors, robotic arms, LIDAR systems or high-quality pan tilt zoom cameras.
“The mine partnered with an American LIDAR 3D-scanning company,” Macdermid said. “We integrated their LIDAR with MIL-SPEC connectors that provide power and Ethernet. With that, we were able to look at real-time LIDAR data at that furthest extent underground using the network we created, which was pretty cool.”
The high-risk nature of the operation meant the engineers maintained manual control throughout.
“The sheer distance and communication difficulties involved because of room and pillar mining was the primary challenge we had to overcome,” he said.
“In the end, it was a matter of getting more robots to extend the range and the communications.”
ADR undertook extensive testing before travelling to the United States to complete the mission, but they were limited to sporting fields as they couldn’t access anywhere with the underground distance required.
“We did a scale test with only three of the robots. Theoretically, the distance between each robot using three or 10 will be the same,” Macdermid said.
“Simulating the setup procedures, monitoring the communications and the signal strength with the software and then determining the minimum requirements for the signal strength that we’d stick to formed the guideline for each robot hop.”
For Macdermid, the technical feat was satisfying, but the human element of their achievement brought it all home.
“It was great to see the impact on the local community over there,” he said.
“We’d go into town and speak to people, and everyone seemed to have a relative who worked in the mines, so we could see the impact of what we were doing straight away.”
Leading the way
ADR’s development comes hot on the heels of Australia’s national science agency (CSIRO) placing second in the Subterranean Challenge organised by the US Government research agency DARPA, where scientists were tasked with developing robots that could rapidly map, navigate and search complex underground environments.
Jonathon Ralston, who leads space resource technology developments at CSIRO, said Australia’s world-class mining sector means the country has well-developed capabilities when it comes to the unique challenges of remotely accessing underground mining sites.
“The key challenge here was to successfully operate a remotely managed robotic asset,” he said.
“This involved several engineering components, including a surface control station, an intuitive user interface, robust communication links, agile mobility platforms, sensors capable of providing insights of the underground environment to provide the required remote monitoring and inspection capability.
“What they’ve managed to achieve is put all those components together to provide that solution for the customer in a tight timeframe.”
On top of that, that the engineers were operating in an uncertain and potentially unstable environment.
“Compared to a surface or open cut mining operation, your robotic mobility platform needs to be very robust and reliable,” he said.
“For example, in some underground scenarios, you may also need to take into account the fact that you might be operating in an explosive environment.”
Ralston added that 25 or 30 years ago, the usual industry response to underground mining incidents was to consider sending in a mine rescue team. However, robotic platforms for remote maintenance and inspection have significantly improved, and today offer credible options that greatly reduce exposure risks for personnel.
Another challenge was creating a communication link capable of providing coverage from the surface to “where the main action is”, which might be kilometres away, Ralston said.
“For typical line-of-site wireless communication networks, communication quality can significantly degrade after only 200 or 300 metres, particularly in an underground tunnel-like environment,” he said.
“To address this challenge, ADR utilised platforms to form a series of nodes and stations, which bridged the gap to provide the necessary communication link. This was a really nice application of wireless technology that they managed to deploy.”
Of course, it was researchers at Australia’s national science agency who invented WiFi in the 1990s, and Ralston was part of the first group in the world to successfully use WiFi communications underground.
He believes further developments in robotics capabilities, along with wireless, are key to improvements in underground mining technology.
“We’ve seen steady improvements in communications performance since then, both in terms of reliability and bandwidth, which is good for the underground scenario,” he added.