Running robot: Mabel is the world's fastest two-legged robot with knees
16 Aug 2011
A robot in a University of Michigan lab can run like a human - a feat that represents the height of agility and efficiency for a two-legged machine. With a peak pace of 6.8 miles per hour, Mabel is believed to be the world's fastest bipedal robot with knees.
"It's stunning," said Jessy Grizzle, a professor in the Department of Electrical Engineering and Computer Science. "I have never seen a machine doing a motion like this."
Mabel was built in 2008 in collaboration with Jonathan Hurst, who was then a doctoral student at the Robotics Institute at Carnegie Mellon University. Grizzle and U-M doctoral students Koushil Sreenath and Hae-Won Park have spent the years since ratcheting up Mabel's training. They've been progressively improving the feedback algorithms that enable the robot to keep its balance while reacting to its environment in real time.
Mabel started off walking smoothly and quickly over flat surfaces. Then it moved on to uneven ground. It took its first real jog in late July, and with that, Sreenath met the ultimate goal of his research just days before he was scheduled to defend his thesis.
Few robots can run, and the researchers say no machine but Mabel can do it with such a human-like gait. Its weight is distributed like a person's. It has a heavier torso and light, flexible legs with springs that act like tendons.
Mabel is in the air for 40 per cent of each stride, "like a real runner," Grizzle said. Other running robots are almost speed-walking. Their so-called flight phase when both feet are off the ground lasts for less than 10 per cent of each step.
"We envision some extraordinary potential applications for legged robot research: exoskeletons that enable wheelchair-bound people to walk again or that give rescuers super-human abilities, and powered prosthetic limbs that behave like their biological counterparts," said developer Hurst, who is now an assistant professor in the Department of Mechanical, Industrial and Manufacturing Engineering at Oregon State University.
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