Thursday, November 29, 2012
2:00 PM - 6:00 PM
Where: Technological Institute, F-160, 2145 Sheridan Road, Evanston, IL 60208 map it
Audience: Faculty/Staff - Student
Category: Lectures & Meetings
Professor of Mechanics, Cornell University
Gliders, Bicycles and Walking Robots
Seminar - 2:00 PM - Tech F-160
Refreshments served at 1:45 PM
Reception - 5:00 PM - Cohen Commons
Co-sponsored by the NU SIAM Student Chapter
Many airplanes can, or nearly can, glide stably without control. So it seems natural that the first successful powered flight followed from mastery of gliding. Many bicycles can, or nearly can, balance themselves when in motion. Bicycle design seems to have evolved to gain this feature. Also, we can make robots that, like a stable glider or coasting bicycle, stably walk without motors or control in a remarkably human-like way. So it makes sense to use "passive-dynamics" as a core for developing the control of walking robots and to gain understanding of the control of walking people. That's what I used to think.
But, so far, this has not led to robust walking robots. What about human evolution? We didn't evolve dynamic bodies and then learn to control them. Rather, people had elaborate control systems way back when we were fish and even worms. But if control is paramount, why is it that uncontrolled passive-dynamic walkers can walk so much like humans? It seems that energy-optimal control, perhaps a proxy for evolutionary development, arrives at solutions that have features in common with passive-dynamics. Rather than thinking of good powered walking as passive walking with a small amount of control added, I now think of powered walking as highly controlled, but with much of the motor action titrated out.
This will all be explained with photos, videos, and a few references to, but not detailed explanation of, real or imagined calculations.