Robot displays mettle in mine
- Robot displays mettle in mine
Saturday, May 31, 2003
By Byron Spice, Post-Gazette Science Editor
As a four-wheeled robot called Groundhog crept slowly into the portal of the Mathies Mine yesterday morning, the Carnegie Mellon University researchers who developed it felt something unusual -- separation anxiety.
They knew that within a few hundred feet, Groundhog would have to make a right turn as it followed the mine corridor and would no longer be in a line of sight with the portal and, thus, would be out of radio communication with them.
Groundhog would be on its own. If and when it emerged from either end of a 3,500-foot-long mine corridor would depend on things the machine could see for itself and decisions it would make for itself.
Roboticists at CMU have built many robots designed to operate autonomously, but yesterday's experiment marked the first time that any of the machines had ventured where humans couldn't intervene to avert an emergency. More than one remarked that it was like sending a child off to college.
"It's tough," said Scott Thayer, a systems scientist at the Robotics Institute, after the 1,600-pound robot was enveloped by the damp darkness. "Tougher than I thought."
"It was kind of sad to see the robot drive away," agreed Cheryl McGill, district manager for the Mine Safety and Health Administration, "but in my heart, I know it will come out."
Groundhog is the first of several robots that the Robotics Institute has developed since August in response to the Quecreek Mine accident. Because that mine inundation appears to have been caused at least in part by inaccurate maps of an abandoned mine, researchers under the lead of William "Red" Whittaker have sought to build robots that could enter mines where no sane person would venture and either draw accurate maps or perform search-and-rescue of trapped miners.
Whittaker claims to feel little sentiment for the machines and would happily send Groundhog back into the Mathies Mine over and over, until it either breaks or gets lost. But he acknowledged he has observed many researchers develop an attachment to their devices.
"I used to think a great addition to the teams would be a psychologist or a grief counselor," he said. But even if he didn't worry about Groundhog when it was out of communication range, he couldn't help but think -- and marvel -- at what the millions of decisions its computer brain was making. "It's just churning away."
Like many experiments, the result of the one yesterday was encouraging to the researchers, if not totally successful. Whittaker and his nine-member crew had hoped to send Groundhog into a portal near Route 88 outside of New Eagle and have it emerge at the other end, the Mathies preparation plant on the Monongahela River.
The state Department of Environmental Protection may need to run a pipe through that tunnel to move excess mine drainage from Mathies to the river site for treatment, so yesterday's experiment could have provided the department with an up-to-date map of the corridor in addition to testing the robot's autonomous skills.
The robot, about the size of an all-terrain vehicle, worked flawlessly much of the time, venturing about 1,000 feet down the mine corridor. It then encountered an obstacle -- a roof beam that had fallen on one side -- and turned around, heading for the entry portal.
"It made the absolutely appropriate decision," said Sebastian Thrun, a computer scientist in charge of its mapping and autonomous systems. Inside the 11-foot-wide tunnel, "there's no way it could have squeezed around the obstacle."
But about 600 feet from the portal, something began to go wrong. Every couple of minutes, Groundhog would stop and reboot its computers, perhaps because of a power problem with one of its systems, Thrun said. Finally, with the machine back within radio range, Thrun and his crew downloaded its maps and attempted to tele-operate it. But then they lost all communication with the robot.
Later, two mine inspectors from DEP and two from MSHA walked into the mine and hit Groundhog's reset switch, allowing the roboticists to regain control and drive it out of the mine.
That the field experiment happened at all was remarkable. Many of the seven students working with Thrun, Thayer and Whittaker had worked virtually without sleep for three or four days before the experiment, and then, all appeared to be lost about 2 a.m. yesterday, when a steering position sensor broke.
The robot needed to be loaded on a truck by 5 a.m. to make it to the Mathies Mine. With no spare sensor available and the steering gear inaccessible, the crew jury-rigged a new one.
Whittaker said Groundhog's days as a lead experimental vehicle are probably limited. To be truly useful, subterranean robots will need to get much smaller, preferably small enough to enter a mine -- or a cave, sewer, pipe, tank or Iraqi bunker -- through a borehole.
One such robot, called Helix, is under development now. Shaped like a cigar, it would be lowered through a borehole into a mine, where it could transform into a four-wheel configuration.
"We think this type of technology will enhance the safety of the district's mines," said William Plassio, DEP's district mining manager. DEP is helping to finance development of robotic sensors that can be lowered through boreholes.
Mathies Mine was closed in April 2002 and has been filling with water ever since. Scott Horrell, DEP environmental program manager, said about 1,200 gallons a minute already are draining from the mine and being treated. But space is limited near the Mathies portal on Route 88 and, if the volume of mine drainage increases, it may be necessary to pipe the orange-brown water through the corridor explored by Groundhog to the old Mathies preparation plant, where more room for treatment ponds is available.