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Beast of burden

Yeti robot tackles crevasse detection in polar regions

 

During the 2010-11 field season in Antarctica, personnel at the South Pole Station used a series of small explosions to collapse several old buildings, which had been buried under the ice for decades but that had become a hazard to surface travel.

The question this past season: Was it now safe to travel over an area known as Old Pole, the first research station built by the United States back in the 1950s?

The U.S. Antarctic Program enlisted Yeti to find out.

No, not the 10-foot-tall creature with a serious hirsute problem. This Yeti doesn’t come with hair — just four wheels, a metal body, a bunch of batteries and high-tech radar. It’s the creation of Dartmouth College’s Thayer School of Engineering, specially designed to operate in the polar regions.

“It worked out great with Yeti,” said Andy Martinez, a facilities engineer for the U.S. Antarctic Program (USAP) who has managed the ongoing project to collapse and permanently bury some of the remaining buildings, which have created voids in the ice, making the surface unstable for operations.

Rather than risk sending people in a heavy vehicle with a ground-penetrating radar (GPR) to survey the site, the lightweight Yeti robot was deployed to image the area.

“Yeti performed a task that would be very tedious and arduous for humans,” said George Blaisdell, the USAP Operations manager in the National Science Foundation’s Office of Polar Programs. “It’s far safer than a human-deployed survey.”

The 160-pound robot, smaller than an all-terrain vehicle, found three additional buildings outside of the original blast zone that appeared to pose additional hazards.

“It was a good thing that the [National Science Foundation] chose to have the site resurveyed. In retrospect, we can see the value of the robot beyond the time savings of manual surveys,” said Jim Lever, a mechanical engineer with the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) who has collaborated with Dartmouth College on the development of Yeti and its predecessor, Cool Robot.

“When you’re doing a survey, you just program the waypoints you want it to follow, and it will happily go about doing that. That’s what we did at South Pole,” explained Lever, who helped operate the robot during its three-day survey of Old Pole in December 2011.

The development of Yeti and Cool Robot — similar to its sibling but solar-powered and intended for long-duration science missions — began nearly a decade ago with a $100,000 Small Grant for Exploratory Research (SGER) from the National Science Foundation (NSF).

The original proposal was the product of a hallway conversation with a space weather scientist at Dartmouth, according to Laura Ray, a professor of engineering at the college and principal investigator on the polar robotics program.

The SGER grant gave Ray, Lever and a team of clever undergraduate students enough resources to design, build and test a solar-powered robot capable of operating months at a time, roving across the icy landscape of Greenland or Antarctica collecting scientific data.

A lightweight chassis built from the same strong and stiff honeycombed material used for airplanes was important to the success of Cool Robot, Ray said.

“It was completely original from the ground up for this given environment. I think that was the key,” Ray said. “If you really want to minimize the energy requirements, you design it from the ground up — and that’s what we did.”

Advances in solar panel technology also helped, along with an innovative design that placed solar panels around the sides of the robot to take advantage of the high reflectivity from the snow-covered surface.

In 2010, Ray, Lever and Mary Albert, also a professor of engineering at Dartmouth, received a second grant from NSF to refine the Cool Robot and send it on a series of long-duration science missions in Greenland for atmospheric research. The engineers are hopeful Cool Robot will also eventually get a shot in the Antarctic.

“I think if we can prove it in one location, it will be a little easier to accept its utility in the Antarctic, too,” Lever said.

Meanwhile, Yeti, which was developed with funding from NASA’s Jet Propulsion Laboratory, has made multiple trips to both poles over the last several years.

Powered by six lithium ion batteries, Yeti is designed for short-duration missions. Its primary work has been in support of overland traverses — tractors pulling sleds of cargo and fuel — in both Greenland and Antarctica by towing a GPR sled across the ice to find signs of possible crevasses, voids beneath the surface that make travel potentially hazardous.

In Antarctica, Yeti spent two previous summers collecting data in an area of the Ross Ice Shelf that has come to be known as the shear zone, for the great number of crevasses that riddle the ice. The South Pole operations Traverse (SPoT) must cross the shear zone every year en route to the bottom of the world to deliver cargo and fuel to the research station.

Yeti was designed and built by Dartmouth undergraduate students, some of whom had a chance to test their robot in both Greenland and Antarctica.

“Our major challenge was to come up with the entire electronics architecture and figure what processes we would use. Basically, build all of the electronics and the mechanical stuff,” said Eric Trautmann, a former Dartmouth electrical engineering undergrad who helped lead the student team. “That was a pretty interesting experience for us.”

Trautmann eventually graduated with a master’s degree from Dartmouth in machine learning and robotics. He is now working on a PhD from Stanford in neuroscience, working on ways to connect neural activity with prosthetics.

However, in 2010, he got a chance to deploy to McMurdo Station for more than a month to work with Yeti in the shear zone, troubleshooting some of the glitches that had emerged the season before.

“It was a pretty cool opportunity to … work in the field and show what Yeti was capable of doing,” he said. “It’s exciting to see it move forward.”

The Old Pole survey marked a significant milestone in the development of polar robots, Ray noted. She said Yeti is filling a real operational need, and it could also be used for research on ice dynamics, a field that makes use of radar surveys.

Blaisdell said the robot’s precision could make it an attractive option for other projects, such as surveying ice runways used by the McMurdo and South Pole stations.

“This task has provided very positive implications for lots of other tedious and exacting USAP tasks,” he said.

Ray said Yeti might return again to Antarctica to collect more data in the shear zone to develop autonomous crevasse detection, a project by Dartmouth graduate student Rebecca Williams.

“We want to continue to demonstrate that the robot has very good potential operationally,” Ray said.

NSF-funded research in this article: Laura Ray and Jim Lever, Dartmouth College, Award No. 0343328; and Laura Ray, Jim Lever and Mary Albert, Dartmouth College, Award No. 0806157.

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Curator: Peter Rejcek, Antarctic Support Contract | NSF Official: Winifred Reuning, Division of Polar Programs