Oct. 4, 1999 After an earthquake or bombing, rescuers who climb into the rubble of collapsed buildings searching for survivors may place their own lives at risk, as well as the lives of unseen survivors hidden deeper beneath the rubble. But a team of North Carolina State University engineers is building a robot to help solve this quandary.
Dr. Eddie Grant, visiting professor of electrical and computer engineering and director of the Undergraduate Design Center at NC State, realized that if robots could get into the building, they would be able to find survivors without endangering the lives of rescuers. Because pipes are often left intact when buildings collapse, Grant conceived the idea of a pipe-crawling robot, and he challenged his senior design students in electrical and computer engineering to build a robot that could navigate pipes.
Under the direction of Grant and Dr. John Muth, visiting assistant professor of electrical and computer engineering, the senior design students created Moccasin I and Moccasin II, robots that can crawl through six-inch piping, using off-the-shelf components.
"The idea for these robots came when I was in Virginia at a meeting," says Grant. "One of the men I was meeting with had been sent in to the Oklahoma City bombing with a marine special force. He told me that the rescuers would have given anything to have a robot that could go in and find the people.
"When I came back to NC State, I realized that this would make an excellent senior design project. And the students met the challenge very well."
The most recent design, Moccasin II, is able to navigate a complicated course of piping, complete with 90-degree turns and vertical climbs. The segmented robot has the look of a cyber-inchworm and uses pneumatics to force padded "feet" against the pipe walls as it extends and contracts its body along the pipe course.
"The use of pneumatics for movement is an important factor because sometimes there are explosive gases present in buildings that have collapsed," says Grant. "Electricity would have the potential for igniting these gases so we designed the robot to use compressed air instead. This gives it added portability, as well. The robot can run off air tanks when there is no electricity to run an air compressor, and it is designed so that it breaks down into components that can be carried easily in backpacks to remote disaster sites."
Moccasin II is outfitted with a tiny video camera and lights that feed video through a cable to a monitor so its location in the pipe can be seen. The robot can also carry sensors that could "hear" or sense vibrations from someone tapping on the pipes.
The on-board video and ability to carry sensors into the pipes makes Moccasin II a versatile robot that could be used not only for search and rescue, but also for repairs on piping in areas where humans would be in danger, such as in nuclear power plant pipes or in gas lines. With other modifications, it could be used to detect cracks in sewer or water lines.
"The robot is very versatile," says Grant. "We are currently working on modifying a different robot based on what we have learned from the Moccasin design. Using compressed air is the key to making a robot that is safer in areas where combustibles are present."
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