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Old 12-01-2012, 12:21 PM   #265
Erick Mead
 
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Dojo: Big Green Drum (W. Florida Aikikai)
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Post Re: Is aiki a clash of forces?

I believe that making swords actually requires hammers and lots of hammering -- and so:

Quote:
Budd Yuhasz wrote: View Post
So, if seeing is believing . . does that mean it has to be felt, too?
What are you feeling ? More importantly, when are you feeling it.

The mystery that drives the degreed physics and engineering types nuts with head-shaking and cranium scratching maneuvers is that -- if my premise is correct -- there is a reflexive circuit involved, and there is a phase lag between action, perception and counter-control input in EVERYTHING involved in these issues.

I happen to be particularly aware of the problems of using voluntary circuitry for physical control because I flew aircraft. Like riding a bicycle -- you cannot use voluntary motor responses to maintain stability -- they are WAAAY too slow -- you need a certain form of reflexive responses -- from much repetitions and refinement of control errors -- but these are polysynaptic reflexes -- just barely within conscious trainability with "muscle memory". That's one level of the problem -- but most people get that -- its like learning to ride a bike -- different from learning to walk -- but not that different.

I summarized the temporal lag aspect in another thread:

Quote:
... for a trained person [using an polysynaptic reflex] -- the order of event, action and perception is:

Stimulus = 0
Polysynaptic reflex = 75ms
Awareness of stimulus = 75ms
Awareness of reflex = 150ms

A monosynaptic reflex, though, is something else (two nerves, one sensory, one motor, one synapse, ...in the land of Mordor , where... never mind...) . These are the tendon reflexes and the stretch reflexes -- which respectively contract or relax a muscle group in response to possibly structurally dangerous loads.

A monosynaptic latency is on the order of 20-45 ms -- call it 30 ms =0.03s, twice as fast as, or even better, as the visual or pain flinch reflexes. Your conscious awareness latency is more on the order of the visual flinch awareness, (75 ms).

Stimulus = 0
Monosynaptic reflex = 30ms [IN]
[No real awareness of structural stress stimulus]
Awareness of reflex = 75ms
Recovery phase of reflex = 50 -100 ms [YO]
Voluntary reaction to reflex 175 ms

This is the sequence that is disturbing to the conscious mind -- because we do not -- without training -- consciously sense or recognize the structural stimulus that causes the reflex. Or we feel it but we do not know at all how to interpret it. It is occurring at a level way below the conscious mind.
Reflex stuffs -- here.

Some engineers are used to temporal phase lag control systems. Most physicists and most engineers outside of rotary wing aviation have not dealt with bodily operated control systems that use both spatial AND temporal phase lag controls. But in our case there is not only a temporal phase lag, but, because this is a complex harmonic system -- there is a spatial phase lag too.

I learned the significance of phase lag control in bodily operated systems because I flew rotary wing aircraft. Sikorsky himself did not anticipate spatial phase lag -- and it took a good bit of puzzling out even for him -- He basically tried to ignore it with a very different control system in the first operating prototype helo, the VS-300.

The aeromechanical problems involved in rotor phase lag are not directly applicable -- but they sensitize you to this class of problem. In most rotary wing craft -- if the controls were spatially in phase with the rotors then the controls would be paradoxical ("non-sourced"). IOW putting the stick forward = tilt the rotor left; left = back; back =left; right =forward. (Reverse the above if you like Aerospatiale -- they go the other way. )

This is a function of the resonance characteristics of a multiple pendulum oscillating system -- not just gyroscopic moments because it spins -- the hinge or teeter SHOULD allow the isolation of gyroscopic precession to the rotor alone -- but the hinge or teeter at the rotor hub creates a resonant connection with the second pendulum of the fuselage -- the resulting moments are a function of the action at the resonant center of both rotations (HINT HINT HINT).

A multiple pendulum is a complex harmonic oscillator and can exhibit resonance (coupled 90 degree phase differences). Coupled oscillators that are 90 degrees out of phase (juji) -- make pretty figures called Lissajous curves -- which just so happen to follow the same class of dual spiral shape and mathematical behavior as torsional shear stress.

Putting all this together --

1) The severe temporal phase lag between structural reflex response and perception requires a feed-forward control.
2) The most damaging structural stresses are torsional
3) Unmodulated reflexive action limb behavior is highly pendular in action
4) Tonic structural stability is dynamic and oscillatory;
5) Refelxive action follows patterns dictated by the most immediate reduction of torsional shear stress
6) The patterns of shear stress and multiple pendulum action are mathematically and physically equivalent -- dual opposed spirals;
7) Feed-forward controls for this system must therefore follow the two dominant patterns involved in the reflex activity:
------ a) pendular spiral action characteristic of resonant multiple pendulums; and/or
------ b) the higher frequency damped stability tonic (~5 or ~10 Hz)
8) Structural reflexes can be potentiated by certain counter-damping stresses (e.g. -- Jendrassik maneuver)
9) Feed forward control patterns can be habituated in voluntary responses that "feed-in" to reflexive action that occurs involuntarily
10 Aiki Taiso (chinkon kishin) are designed to train, respectively the feed forward patterns of both (7a) the "demon snake" and (7b) the "spirit of bees"
11) Koyku tanden ho paired exercise (and Endo's modified atari exercsie)is designed to prompt, potentiate and exploit reflexive structural stresses and cues in both parties and to develop feed-forward voluntary responses that play upon the involuntary reflexive activity (and the tonic damping changes) thus prompted in the opponent and potentiated in oneself.
12) The IS/IP are methods related to (11) but which particularly work on the potentiating aspects of this form of tonic action in the body (7b), and which seem to depend primarily upon manipulating the tonic damping changes with counter-potentiating stresses responding to the applied stresses, rather than or in preference to (7a) feed-forward followups to reflexive mechanical responses to the applied stresses.

Last edited by Erick Mead : 12-01-2012 at 12:25 PM.

Cordially,

Erick Mead
一隻狗可久里馬房但他也不是馬的.
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