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Old 07-29-2009, 01:42 PM   #382
Erick Mead
 
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Dojo: Big Green Drum (W. Florida Aikikai)
Location: West Florida
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Re: Is It Missing In Everybody's Aikido?

Quote:
Mark Murray wrote: View Post
Anyone here with a Ph.D. in Physics want to post the equations for when a human goes from a walk cycle to a run cycle? Ain't gonna happen because no one out there can do that yet. Why do you think the major animation studios use motion capture instead of software based programming? The former is more realistic and the latter takes huge amounts of time to make realistic, bypassing physics altogether.
Heh. It wouldn't do you any good because it is a nonlinear function. This comes close.

The thing about gaits is that they undergo phase transitions. That is what you are talking about. See here: A sudden and discontinuous change in the stability state of the structure of a material, or the dynamics of a system (which are the same thing, actually). Phase transitions are what happens when water changes to vapor and vapor to plasma --and plasma is otherwise called -- "fire" ...

Oh, pish, --- Fire and Water? Silly me, that can't possibly mean anything ... never mind.

The more interesting thing in that second study is this part:

Quote:
these intrinsic dynamics serve as an important characteristic of a
motor system that is coupling to oscillatory perceptual information in the environment. A
classic experiment by Schmidt, Carello, and Turvey17 has shown that when finger
twiddling becomes leg swaying, these phase transitions between rhythmic modes can
even occur between people.
They had pairs of participants each sway a single leg while
seated beside each other. When they were able to perceive each other's leg movements,
the same phase tendencies as in Fig. 2 were exhibited by this two-person system.
Moreover, when subtle modulation of metronome rate occurs (even unbeknownst to
subjects), rapid compensation can occur in the relative asynchrony of tapping shown by
participants.18,19 For example, while participants tap to a metronome pulse, inter-pulse
intervals that change by +/- 10ms can be rapidly compensated for within just 2 or 3 taps.

This may be interpreted as rapid and "subliminal" phase transitions in sensorimotor
coordination. In fact, the same sorts of phase transition seen in these intrinsic motor
dynamics can also be shown in the dynamics of visual perception.

Cordially,

Erick Mead
一隻狗可久里馬房但他也不是馬的.
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