A small robot designed to search for six miners trapped in the Crandall Canyon Mine has taken on a tough job.
"It's basically a custom-built robot," said Matt Faraci, spokesman for the federal Mine Safety and Health Administration. A Canadian company, INUKTUN, worked on the remote-controlled device, he noted.
The robot is the design of the Center for Robot-Assisted Search and Rescue at the University of South Florida in St. Petersburg. The center has produced micro-aerial vehicles to fly over disaster areas, such as the devastation from Hurricanes Katrina and Wilma, and ground robots to search the rubble of the World Trade Center. It has developed larger devices to bring medicine and food into dangerous sites, and robot boats, used after Wilma.
The Crandall Canyon robot looks something like a small tank, with its treads. It measures about 36 inches long by 8 inches wide and 6 inches high. Instead of artillery, it carries a long camera that is to be folded over the robot's body while it is lowered through the drill hole, which is just under 9 inches in diameter.
"Due to the size of the borehole, you're limited to the size of the platform," said Sam Stover, the center's director of operations.
Once inside the mine cavity, the camera is unfolded to look ahead. The robot carries lights that are bright enough to allow it to illuminate 30 to 50 feet of the mine interior.
The tread will allow the robot to trundle over debris up to 4 inches high, but pieces of material larger than that will require maneuvering around. At the surface, an operator can use a joystick to direct the vehicle.
The operator's controls have "a 4 1/2-inch-diameter screen that shows him the feed from the robot," Stover said.
The cost of constructing the robot was approximately $100,000, he said.
"What makes this problem very difficult to solve is the length of tether needed," Stover said. "Typically we don't drive or use these things" with such a long tether. Before this, a typical length would be about 300 feet.
To design the robot, he talked with experts in Australia, South Africa and the United Kingdom, "the who's who of rescue. We have tried to solve this problem."
INUKTUN developed a 3,000-foot tether for the Crandall Canyon effort. In this case, the borehole may be around 1,900 feet deep, and the robot needed another 1,000 feet of tether so it could drive along the shaft. But that brings up a question about whether the robot has enough power to "drag that much tether."
A robot platform has been used for pipe inspection, and has performed well. Special difficulties are expected in the mine, however.
"It's just the debris that creates the problem, any snag points." Designers were concerned that the robot could be hung up on "the reinforcing wire they use in the mine itself," Stover said.
"This is a nasty environment there."
Firm's mine robots work like tiny tanks
Three kinds of mine-disaster robots have been developed by CRASAR over the years, all of which work like miniature tanks:
The "micros" are shoe-box size, to fit into small shafts and voids too small for humans.
Bomb-squad type robots range from the size of carry-on luggage to a small footlocker. They can go into voids that a person might fit into but which would be unsafe for humans. These could be places where an additional collapse is possible, or where hazardous gas is present.
Construction or ship firefighting robots are the size of a small bulldozer, often with arms. They are being developed by Japanese experts for rapid removal of rubble but have yet to be used.
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