Robot Special: Walk This Way
From: New Scientist - 02/04/2006 - Vol. 189, No. 2537, P. 40
By: Philip Ball

Only recently has the concept of passive walking robots - machines that can
imitate a human's entire gait cycle by relying on leg motion and gravity
rather than motors - gained prominence, and an important sign of the
technology's increasing distinction was the unveiling of three passive
walkers at an American Association for the Advancement of Science conference
last February. A team led by Cornell University's Andy Ruina built a robot
that mimics people's ability to pump their gait by pushing off their back
foot at the beginning of each step by using a spring in each lower leg; a
small motor stretches the spring, which causes the ankle joint to flex when
released. Another robot, built by MIT researchers supervised by Russ Tedrake,
can sense the tilt of its body and other factors in order to "learn" how to
walk, using an on-board computer that adjusts command signals transmitted to
electric motors that flex the ankles. The third robot was the product of the
Delft University of Technology in the Netherlands: The device is driven by
compressed-air actuators in the hips, and features an ankle design influenced
by skateboard suspension principles that adds stability. All three machines
represent a significant advance because they simplify leg design and control,
and lower energy consumption. Passive walkers' inability to steer or avoid
obstacles, as well as their difficulty in dealing with uneven or pliable
surfaces, makes them inappropriate models for robust walking robots,
according to Carnegie Mellon University roboticist Chris Atkeson. He believes
the best solution will mix principles of both passive dynamic walkers and
powered walkers, and expects practical robots will be driven by most if not
all of their joints. Passive-walking robots are also inspiring research into
advanced prosthetics that could perhaps reduce the energy cost to the wearer
and amplify human performance. 

Read the article's preview at:
http://www.newscientist.com/channel/mech-tech/mg18925371.900

Links:
Andy L. Runia
http://www.tam.cornell.edu/Ruina.html
http://ruina.tam.cornell.edu/

Andy L. Ruina - Research
http://ruina.tam.cornell.edu/research/

Andy L. Ruina - Locomotion and Robotics - Overview
http://ruina.tam.cornell.edu/research/topics/locomotion_and_robotics/overview.htm

Walking Robots
http://www-personal.engin.umich.edu/~shc/robots.html

The Mechanics of Foot Travel
http://www.nsf.gov/news/news_summ.jsp?cntn_id=104454&org=NSF&from=news

Dynamic Walking 2006
http://www.dynamicwalking.org/

Russ Tedrake
http://groups.csail.mit.edu/locomotion/russt.html

MIT Robot Locomotion Group
http://groups.csail.mit.edu/locomotion/index.html

Teams build robots that walk like humans
http://web.mit.edu/newsoffice/2005/robotoddler.html

Christopher G. Atkeson
http://www.cs.cmu.edu/~cga/

