NMT researchers develop new mine rescue technology

The project is funded by the National Institute for Occupational Safety and Health, and the researchers are collaborating with technology developers and two other universities—the University of Arizona and the University of Nevada, Reno. The University of Missouri Science and Technology is also working on the project. There are 11 Tech students working on the problem as well.

The researchers are developing an unmanned underground vehicle (UGV) that can be sent in before rescuers. The UGV would carry a drone, which could access even more areas in the mine. The robots include sensors to find hazards like collapsed roofs, fires, and concentrations of noxious gases. Exposure to these toxic gases can be deadly.

That information would be relayed to rescuers, so that they do not go into an unknown situation.

The researchers are in the second year of the four-year project, which could be extended an extra year.

They hope their technology will help rescuers navigate the situation faster and give trapped miners information to help them escape.

“So, we don’t expose the mine rescuers to extra danger in an environment where we may have toxic gases, fires and roof collapses,” said research scientist Vasilis Androulakis.

Mine fires, collapses and explosions have declined over the decades with improved safety regulations, but those emergencies still happen and are very dangerous.

“It’s still very hard to evacuate as fast as you can from an underground mine,” said Androulakis.

New Technology

Their first challenge was mechanical: build a housing platform on the UGV for the drone.

“This box is going to house the drone and give it the ability to recharge its battery if needed and also keep it safe,” said Androulakis.

The UGV would drive inside the mine as long as possible, then the drone would take over.

“As the robotics system navigates inside, it needs to collect data like carbon monoxide concentration, or if there is a fire, or if there are other noxious gases and roof falls,” said Androulakis.

Then the information about these hazards would be relayed to rescuers, to help them save time navigating in an unknown, and often complicated, environment. That requires software that makes using the technology in an emergency situation easy for everyone relying on it.

To build this interface, the researchers are considering human decision-making in an emergency situation.

“Because in a very dangerous, harsh situation, emergency situation, the command centers, they need very easy-to-understand information,” said research scientist Hassan Khaniani.

They are surveying people who work in those rescue situations, which will let them design a human-machine interface that will give the user to the most useful information without overwhelming them.

Along with an interface, the researchers have to create a communication system that can get information from the robots to the miners and the rescuers.

“We have two ways to evacuate trapped miners. One way is to send something from outside inside,” said Androulakis. The other way is for the trapped miners to use information and training to decide on the best route out.

To help miners escape, the drone could lead them to a safe zone. But the miner might not have any device—or any remaining battery power—to communicate with the drone, so they are developing a battery-free communication channel.

This UGV is a mine exploration vehicle that houses a drone. The drone can be deployed to reach trapped miners in areas that the UGV cannot reach during a rescue operation.
Courtesy photo

The drone would have a light, and the researchers are developing a system that would collect that light energy.

“This amount of energy would be sufficient to drive a device we call the liquid crystal shutter that is very similar to all the screens our digital devices have,” said Sihua Shao, assistant professor of electrical engineering.

They are also developing technology for a temporary wireless network that would allow rescuers to get real-time information from the UGV, said Shao. The UGV would drop communication nodes as it traveled in the mine to create the network.

They are also creating a virtual reality mine environment that can help train rescue teams, a software and hardware challenge.

“Right now, we plan to add some devices that can measure oxygen levels and blood pressure,” said associate professor Mostafa Hassanalian, that can be used in the virtual training.

Building a drone that can fly in mines

The Mine Safety and Health Administration has strict requirements for technology introduced to a mine, especially in coal mines, making it complicated to build a drone that can operate within a mine.

“Any object which goes to an underground mine, should have a zero percent hazard to the environment. Specifically in coal mines, your electronics cannot get overheated. The propellers of the drone, they shouldn’t create any spark, because you’re dealing with a hazardous environment,” said Hassanalian.

In a separate project, David Wetz, a professor of electrical engineering from University of Texas at Arlington, is collaborating with the team to build a drone that is allowed inside underground mines.

“It’s quite challenging. A lot of companies have tried it. We are trying it too,” said assistant professor Pedram Roghanchi.

Wertz is developing the batteries. The equipment can’t overheat, generate sparks or create fire.

“We have designed a container, which all the electronics go inside that…now the problem is the propellers,” said Hassanalian. “The motor should be connected to the propellers so they can rotate.”

Propellers have to be outside the container to operate, so they are using magnetic couplers to connect the propeller to the motor. That allows the propeller to be outside, while keeping electronics inside.

A multi-disciplinary approach

Mines are complicated environments. Mining accidents usually don’t have just one cause, and the researchers are bringing knowledge from different fields together to build technology that can help save lives after a mining accident.

“Hassan has a background in geoscience. He’s bringing all that knowledge to mining. Vasilis has a mining background and an automation background he is bringing to the table. Mostafa is mechanical engineering. We have electrical engineering as well,” said Roghanchi.

Looking at a problem from different perspectives can make it easier to solve, which is why multi-disciplinary research is so important.

Editor’s Note: Researchers wanted to clarify that the coupled UGV-UAV system under development does not have the functionality to directly communicate or indirectly relay information to the trapped miners besides the liquid crystal display (LCD) shutter technology, which Shao is developing. The LCD shutter technology works when the drone is in the vicinity of a human.

Although, one part of the project aims to develop smart self-evacuation techniques for the trapped miners, the information that will be used as input to these is not acquired through the UGV-UAV system.