Page 57 - Modern Robotics Building Versatile Macines

LEARNING TO WALK 37

legged system can choose among the footholds in the reachable terrain;
a wheel must negotiate the worst terrain. A ladder illustrates this point:
Rungs provide footholds that enable the ascent of legged systems, but
the spaces between rungs prohibit the ascent of wheeled systems.

Additionally, Raibert pointed out that with legs, the main body
(and whatever it is carrying) can move independently of the propul-
sion system—thus a pizza delivery person can walk up stairs while
keeping the pie level. Finally, of course, with legs, one can step over
obstacles that would stop a wheeled cart in its tracks.

Making of an Engineer

Marc Raibert was born in New York City in 1949. He graduated
from Northeastern University with a bachelor’s degree in electrical
engineering in 1973, receiving a
doctorate from the Massachusetts
Institute of Technology (MIT) in
1977. Raibert then worked at the
Jet Propulsion Laboratory (JPL)
in Pasadena, California, as a staff
engineer from 1977 to 1980. JPL
was (and is) the nation’s foremost
center of research and development
in space robotics, including plan-
etary probes and rovers. Working
there spurred Raibert’s interest in
finding better ways for robots to
move across terrain.
In 1981, Raibert went to Carnegie
Mellon University, where he was an
associate professor of computer sci-
Marc Raibert’s research has drawn
ence and robotics until 1986. Raibert
on animal locomotion to develop
established the Leg Laboratory for
legged robots that can walk, hop,
the study of legged robot locomo- and even run dynamically. (Photo
tion. He then went to MIT, taking courtesy of Marc Raibert)