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Old 12-01-2006, 03:25 PM   #320
Erick Mead
 
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Dojo: Big Green Drum (W. Florida Aikikai)
Location: West Florida
Join Date: Jun 2005
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Re: Aikido: The learning of natural movement

Quote:
David Knowlton wrote:
have you studied tensegrity principles or examples of tensegrity structures to help you understand human physiodynamics?
Statically, I know they have obvious application as to the integrity of limb structure and static stability, and much that seems counter-intuitive because most people's "force path" assumptions tend to be all of one sign rather than merely of one sign "on average" along any arbitrary load path as in tensegrity structures. They are really just complex space frames with dedicated tensile or compressive components, which can be seen if you recognize the irregular but still tetrahedral and octahedral nodes in those structures. Dynamically, I think other principles predominate.

Quote:
David Knowlton wrote:
ps. challenge yourself to prove why a bicycle works. attempts to isolate 'the principle' have resulted in some comical bicycles - eg. a machine with a ridiculously small front wheel (moment of force principle) - the front wheel caught fire, but the bicycle stayed up. Good luck sir! dk
Bicycles stay up because they have sufficent angular momentum to slow (but not eliminate) lateral tipping forces caused by a certain allowable range of eccentric lateral loads from the rider, which allows the rider sufficent reaction time to adjust the load profile to maintain stability.

The slowing moment is provided because the input lateral tipping moment is translated gyroscopically by the momentum of wheel rotations from the transverse axis into the yaw axis and thus is mechanically countered by a moment arm of the frame formed between one wheel and the other, and a torque resistance against actual yaw rotation from friction with the ground, and the countering reaction forces created by that torque are translated back to the lateral axis by the same path.

QED

Turning is left as an exercsie for the class...

Cordially,

Erick Mead
一隻狗可久里馬房但他也不是馬的.
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