Prosthetics research to be based on simple robotic motions

• Simple robots that toddle along like an old-fashioned child's toy offer a more realistic and efficient model of human walking than more sophisticated models, researchers said on Thursday.
• They hope their back-to-basics approach can be used not only to design more efficient robots, but also prosthetics for injured patients and amputees, and to understand better how people walk.
• The idea is based on "passive-dynamic walkers" -- devices that can walk down a slight slope using only gravity and carefully balanced, pendulum-like legs.
• These unpowered walkers can produce a surprisingly human-like gait, three separate teams of researchers report in this week's issue of the journal Science.
• Adding a tiny bit of power, as much as is used by a small fluorescent light bulb, allows an element of control for the walker to make more than a few steps and adjust to differing terrain, including level ground.
• "We can let the mechanics take care of a lot of the motion as opposed to motors," Andy Ruina of Cornell University in New York, who helped design one of the robot walkers.
• "For a robot to ever be practical it has to be able to run for a while," Ruina told a news conference sponsored by the American Association for the Advancement of Science.
• The concept is simple, said Ruina -- the legs act like sticks attached to hinges, and swing back and forth with a pendulum motion.
• "Mainstream" robots, on the other hand, have every movement carefully controlled and powered.
• Steven Collins of Cornell, who is now at the University of Michigan, added a tiny bit of motorized propulsion at the robot's ankles.
• "At each step it pushes off with its back foot," Collins said.