Quote:
Mark Murray wrote:
Actually, no. In fact, the reference you cited disproves your whole argument. Let me quote:
"Other considerations, however, reveal limitations to the pendulum model. It successfully explains differences in energy exchange between walking and running, but it does not quantitatively explain how they should vary as a function of walking speed. For example, as speed increases, there are changes in the kinetic and gravitational potential energy exchange34 and the stance leg appears to behave less like a pendulum, but the pendulum analogy does not explain why this is the case. It gives no reason why longer and faster steps (up to the theoretical maximum walking speed) should require a different amount of mechanical work and force than shorter and slower steps. Taken literally, pendulum mechanics predict that a step requires no work or force whatsoever.17 Once walking has commenced, there is no reason why work must be performed to maintain the conservative motion. The pendulum analogy also does not apply to double-limb support, where a pendulum (inverted or otherwise) clearly cannot swing. Although the pendulum analogy is important for understanding how walking can be economical, it does not explain why walking costs energy at all. In that respect, the inverted pendulum model is incomplete."
Your whole inverted pendulum model falls apart at just a cursory glance. As soon as you look at it in a complex model, especially the human body ... well, you have a better chance at winning the Powerball Lottery ... twice in a row.
Do you really want to get into "simple harmonic oscillation", which by its definition has no real forces acting on it? For example, "In real oscillators, friction, or damping, slows the motion of the system. Due to frictional force, the velocity decreases proportional to the acting frictional force. Whereas Simple harmonic motion oscillates with only the restoring force acting on the system, Damped Harmonic motion experiences friction." You are basing your theory on a simple model that is used in unrealistic conditions, let alone based upon the human model. Your "simple harmonic oscillation" falls apart at just a cursory glance.
No, the physics doesn't say so. Your models have never shown any basis in the theoretical world for working, let alone the complex, real world of the human body.
AND THEN, when someone actually does gain the required knowledge (and wins a Nobel prize for it) of how the human body functions in relation to the physics world, that will only determine the majority of people, not those rare, unique martial artists who have IP/aiki. All real world tests to this date have shown that these people's body functions entirely differently than normal people.
And no, Ueshiba didn't say so. Current literal translations show that Ueshiba stated and restated ancient martial training theories in regards to IP/aiki.
But, all this is off topic. Please start a different thread if you want to continue trying to use physics in regards to aikido.
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Incomplete != wrong. Iterated, cumulative approximations are the foundation of learning and understanding anything, including human kinematics, aikido and IP. Basic models may not explain everything all at once, but they do describe portions of phenomena sufficiently to make confident, reliable conclusions and predictions. And, most importantly, the models themselves suggest improvements for creating future models that are more accurate, capture more reality, and lead to even better desciptions and predictions.
What will happen, what will the physics denier say, when someone does bother to do a broad and deep study of an IP practitioner's movement, and what the practitioner is doing is explained by biomechanics? There seems to be a strong need in some folk to keep very special what they do vs what other people do.
The moment the word "force" was first introduced into this conversation, physics stuck its head into the room. If we all train for different reasons and that's ok, we all also should have the freedom to understand and discuss what we do in different ways. Physics is an excellent framework for discussing movement in the real world. It absolutely belongs in this discussion.