ITHACA, N.Y. -- It doesn't have a brain or a heart, and its walk is a little like the scarecrow's, but a little headless, armless, trunkless two-legged robot, developed at Cornell University, can walk, wobble, hobble, limp, stride and stagger. But it can't stand still in any position without falling over.
The fact that this robot, made of plastic Tinkertoy parts and a few odds and ends, is stable in motion is giving mechanical engineers here new thoughts about how humans walk.
Michael J. Coleman, a lecturer in mechanical engineering at Cornell, says the little walker, by using gravity on a gentle slope "performs repeatable, chattering, human-like stable steps without falling over." Says Coleman, who earned his doctorate in February, "We believe this is the first two-legged, statically unstable 3-D passive-dynamic walker that can walk stably down a slope without any control system whatsoever."
With help from Andy Ruina, director of the Human Power, Biomechanics and Robotics Laboratory at Cornell, Coleman stumbled on the walker's design while preparing for his doctoral defense. "In fact, it is one of the few devices of any kind that is dynamically stable near a statically unstable configuration and doesn't have fast spinning parts," says Ruina.
"Playing, with no hopes of success, we placed the toy on a ramp. Surprisingly, it took a few serendipitous, if not very steady or stable steps. After some nonquantifiable tinkering, we arrived at the functioning device," Coleman and Ruina write in the April 6 issue of Physical Review Letters, in which they describe their contraption. Their work also was presented recently at a conference in Germany on the mechanics of walking.
"How humans walk with their top-heavy, upright trunk atop two relatively spindly legs is not well understood," explains Coleman in Ruina's third-floor lab where robot legs and dismembered bike wheels chains and spare parts dangle from the ceiling and are strewn about th
Contact: Susan S. Lang
Cornell University News Service