Mirroring Motion
Robots gain agility by watching their makers.
From: Technology Review - March 2003 - page 29
By: Gregory T. Huang


At the Advanced Telecommunications Research Institute in Kyoto, Japan, a
million-dollar humanoid robot is learning to play air hockey. Using stereo
video cameras, "DB" watches as a researcher strikes the puck with his paddle.
Then using its hydraulically powered arm, the robot imitates the motion.
After a few false starts, DB is able to hit the puck, and its movements are
surprisingly graceful. This sort of "imitation learning" is yielding smarter,
more adaptive robots for physical therapy, search-and-rescue missions, and
space applications. 

Imitation learning combines artificial-intelligence software with
cutting-edge neuroscience. To learn arm movements for air hockey - or even
for hitting a tennis ball - the robot uses machine vision algorithms to
determine the position and velocity of a person's limbs and maps this
information to its hydraulic joints. Comparing its own movement with the
origi- nal, the robot makes adjustments in real time. This is a more
efficient way to make a robot perform human tasks than brute-force
programming or trial and error, says computer scientist Stefan Schaal of the
University of Southern California. Schaal is teaching DB new tricks in
collaboration with the Japanese research group, Carnegie Mellon University,
and Sarcos, a robotics company in Salt Lake City. 

Until recently, however, "There was a large component of Simon Says with
these robots. They didn't understand what they were doing," says Carnegie
Mellon robotics expert Chris Atkeson. Changing one of their familiar tasks
even slightly, in other words, would befuddle the machines. To add
flexibility, researchers are now teaching robots to divide movements they've
seen before into pieces that serve intermediate goals. Robots can learn to
splice these building blocks together to adapt their behaviors - reaching,
balancing, and even walking - to new situations. Within a few years, says
Schaal, such resourceful robots could perform hazardous rescue missions,
analyze stroke patients' movements to help them refine motor skills, and
replace space- walking astronauts on repair missions. 

http://www.technologyreview.com/articles/innovation70303.asp