Monday, April 23, 2012

The world's first two-legged robot with a trip reflex

The two-legged robot named MABEL can now recover from a stumble like a person, making her the world's first robot with a trip reflex, University of Michigan researchers say.

The fastest bipedal robot with knees can now step up onto a platform that's in her path. She has no cameras, so she uses a sense of touch, so to speak, to keep steady footing.

"No other bipedal robot out there could do this, and I am pretty sure that most people would face plant as well," said Jessy Grizzle, a professor in the Department of Electrical Engineering and Computer Science and MABEL's creator.

Hae Won Park, a doctoral student in the Department of Electrical Engineering and Computer Science (who defended his thesis last week), programmed the robot to operate in this way. First, he researched the literature on how humans use their feet to catch themselves from falling. People have two different strategies, Park explains. If they stumble early in the swing phase of a step, they quickly lift that leg. If they trip late in the step cycle, they abruptly lower the swing leg and then raise the other.

The researchers added sensors to the front of MABEL's legs to give her a better feel for what she's encountering. With this added sensory information and some brand new algorithms, the bot can now keep solid footing in the face of a four-inch platform. She plants right on top of it.

MABEL has been walking well on level ground since summer 2009. She took up running in August 2011 and later that year could step down, without warning, from an 8-inch height without falling. A standard US stair is 7 3/4 inches. In her latest video, she shows off several of these skills as she
saunters deftly through an obstacle course of boards.

This research could pave the way for two-legged robots that perform rescue missions. Such robots would need to be able to walk up and down stairs, step over toys on the floor of a burning house, for example, or navigate through rocks in a war zone. These ideas aren't far-fetched. Just last week, DARPA announced a $2 million Robotics Challenge for a disaster-response bot that can aid in a nuclear emergency scenario. Here's how the New York Times explains the contest:
...(T)he Defense Advanced Research and Planning Agency, or Darpa, lists eight likely tasks the robot will need to perform — among them driving a vehicle to a simulated disaster site, moving across rubble, removing rubble from an entryway, climbing a ladder, using a tool to break through a concrete wall, finding and closing a valve on a leaking pipe, and replacing a component like a cooling pump.
To be continued....

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