Cal Poly Pomona

Physics Seminar

Friday, February 3, 2006

Stick balancing at the Fingertip: Insights into the Neural Control of Balance

John Milton

William R. Kenan Jr. Professor of Computational Neuroscience
Claremont Colleges

It is likely that everyone has tried, at one time or the other, to balance a stick, such as a pencil, at their finger tip. However, few think about the underlying physics of this task and even fewer about how the nervous system tries to exert control to keep the stick balanced as long as possible. For example, the fact that longer sticks are easier to balance than shorter ones arises because it takes time for the nervous system to detect the vertical displacement angle and make a correction: once the stick becomes sufficiently long its rate of movement becomes slow compared to the correction time and hence balancing becomes easier. But then why does the stick still eventually fall?; why do people get better with practice?; and why does stick balancing improve in some people if they concurrently move their leg rhythmically, or, for that matter, just think about moving their leg? The purpose of this presentation is to demonstrate that by combing high speed motion capture techniques with simple experiments and a little mathematics we arrive at the surprising conclusion that the answer to these mysteries is related to the fact that noise plays an important role in the neural control of stick balancing. This insight has important implications for problems ranging from the design of two-legged robots to devices to prevent falls in the elderly to the development of expertise in the performance of motor tasks, such as the golf swing.

Refreshments at 4:00 PM. Seminar begins at 4:10 PM.
Building 8 (Science Bldg.) - Room 241
For further information, please call (909) 869-4014

Last modified on January 4, 2006
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