Climbing Robot Can Aid in Surveillance

Wednesday, August 11, 2010 @ 06:08 PM gHale


Wielding two claws, a motor and a tail that swings like a grandfather clock’s pendulum, a small robot named ROCR (“rocker”) can climb up a carpeted, 8-foot wall in just over 15 seconds.
“While this robot eventually can be used for inspection, maintenance and surveillance, probably the greatest short-term potential is as a teaching tool or as a really cool toy,” said robot developer William Provancher, an assistant professor of mechanical engineering at the University of Utah.
Most climbing robots “are intended for maintenance or inspection in environments such as the exteriors of buildings, bridges or dams, storage tanks, nuclear facilities or reconnaissance within buildings,” Provancher said.
But until now, researchers did not design most climbing robots with efficiency in mind, rather only to not fall off the wall they are climbing.
“While prior climbing robots have focused on issues such as speed, adhering to the wall, and deciding how and where to move, ROCR is the first to focus on climbing efficiently,” Provancher said.
One previous climbing robot could ascend about four times faster than ROCR, which can climb at 6.2 inches per second, but ROCR achieved 20 percent efficiency in climbing tests, “which is relatively impressive given that a car’s engine is approximately 25 percent efficient,” Provancher said.
Researchers define the robot’s efficiency as the ratio of work performed in the act of climbing to the electrical energy consumed by the robot, he said.
Other researchers have studied a variety of ways for climbing robots to stick to walls, including dry adhesives, microspines, so-called “dactyl” spines or large claws like ROCR’s, suction cups, magnets, and even a mix of dry adhesive and claws to mimic wall-climbing geckos.
Now that various methods have been tried and proven for robots to climb a variety of wall surfaces, “if you are going to have a robot with versatility and mission-life, efficiency rises to the top of the list of things to focus on,” Provancher said.
Nevertheless, “there’s a lot more work to be done” before climbing robots are in common use, he adds.
ROCR is small and lightweight: only 12.2 inches wide, 18 inches long from top to bottom and weighing only 1.2 pounds.
The motor that drives the robot’s tail and a curved, girder-like stabilizer bar attach to the robot’s upper body. The upper body also has two small, steel, hook-like claws to sink into a carpeted wall as the robot climbs. Without the stabilizer, ROCR’s claws tended to move away from the wall as it climbed and it fell.
The motor drives a gear at the top of the tail, causing the tail to swing back and forth, which propels the robot upward. A battery is at the end of the tail and provides the mass that is necessary to swing the robot upward.
“ROCR alternatively grips the wall with one hand at a time and swings its tail, causing a center of gravity shift that raises its free hand, which then grips the climbing surface,” the study says. “The hands swap gripping duties and ROCR swings its tail in the opposite direction.”
ROCR is self-contained and autonomous, with a microcomputer, sensors and power electronics to execute desired tail motions to make it climb.
Click here for a video showing the robot climbing.



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