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Old 04-01-2003, 07:26 PM   #1
El Spamo
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Lightbulb Physics and Aikido

I'm currently doing a school project that explores the significance of physics in Aikido. I was wondering if anyone around here is willing to post useful links, book suggestions or raw information to help out with the project.

Thanks in advance for whatever information you give.
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Old 04-01-2003, 08:02 PM   #2
aikidoc
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You might try the Dancing Wu Li Masters by Zukov. It's not aikido but it relates physics to some of the issue like ki or spirituality.
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Old 04-01-2003, 09:39 PM   #3
ralphbecket
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Gravity, Levers, Momentum and Torque

(Disclaimer: I've only been studying aikido for eight months.)

It seems to me that many aikido techniques depend upon the following principles (I'm assuming that physics, here, does not include the use of pressure points and I do not accept that there is anything mystical about ki.)

(1) Levers

Essentially, a lever allows a small force applied over a longer distance (i.e. further from the fulcrum) to have the same effect as a greater force applied over a shorter difference (i.e. closer to the fulcrum.)

Examples: morote dori kokyo ho, juji garame, bokken.

(2) Gravity and Centre of Mass

Gravity effectively exerts a constant force downwards through the centre of mass. If the COM is shifted off the line where the feet are placed then this force is experienced as torque and will work to bring someone down.

Examples: morote dori kokyu ho, forward rolls.

(3) Momentum

It takes the same amount of work (i.e. force applied over distance) to lose horizontal momentum as it does to acquire it. Hence opposing momentum directly is hard, but gently adding to momentum (and slightly redirecting it to shift the COM as in (2) above) is relatively easy.

Examples: irimi nage, kote gaeshi.

(4) Torque and Moment of Inertia

Essentially the same things as force and momentum in the rotating frame. Rotation also brings with it the phenomenon of centrifugal force: someone moving around the edge of a circle at speed will experience an outward force; a person turning at the centre of the circle will not.

Example: dai ikkyo ura waza.

Hope this helps,

- Ralph
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Old 04-01-2003, 10:03 PM   #4
bob_stra
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Re: Physics and Aikido

Quote:
Pat W. (El Spamo) wrote:
I'm currently doing a school project that explores the significance of physics in Aikido. I was wondering if anyone around here is willing to post useful links, book suggestions or raw information to help out with the project.

Thanks in advance for whatever information you give.
Well, firstly, yes such things do exist. On the net even.

Secondly, I've been stupid enough not to bookmark them ;-( I recall reading a MSc project on this topic once...perhaps the link is over at www.aikidofaq.com

Thirdly, there are tons of judo books on this very topic (eg: The biomechanics of judo). Though of course, re: judo throws.

http://members.tripod.com/~HappyCloud/

Fourthly, I think Tim Catmell's Effortless combat throws might be of use to you.
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Old 04-02-2003, 07:23 AM   #5
Veers
 
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I'm working on an aikido research paper, and I found an interesting article while looking around at the library.

I can't remember which magazine it was in, but if you go to the 1982-86 periodical listings and look up "aikido" there was an article on the physics of aikido (might've been called that, too. I don't konw, because all but the last page was ripped out of the magazine), but it had some drawings and explinations. Take a look for that.

The early bird may get the worm, but the second mouse gets the cheese.
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Old 04-02-2003, 08:16 AM   #6
ikkainogakusei
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Re: Physics Biomechanics Aikido

Quote:
Pat W. (El Spamo) wrote:
I was wondering if anyone around here is willing to post useful links, book suggestions or raw information to help out with the project.
Hello...uh do you go by Pat or 'El Spamo' online?

I am currently doing a biomechanical study of the Aikido forward roll. You may want to consider that mechanics and biomechanics are rather different in that the purely mechanic has more measureable physics whereas biomechanics still has several areas which are very difficult to take into account.

Right now, for example, since I'm not using force plate analysis (next semester, in quantitative analysis of mvt) I can't get true Ground Reaction Force data, but can get an analogy of it if at a moment of time there is only 1 point touching ground ( e.g. one foot versus 2).

The subtlty of response due to muscular contraction and how it is distributed across a system will have an affect as well, though if you are simply looking for general physics concepts and how they are applied the Martial Arts Book of Physics might help. It doesn't really go into detail in biomechanics but does talk about general physics concepts through martial arts. It has some really great 70's and 80's era stock photos (though poor print quality) of people like Benny 'The Jet', and Bill 'Super Foot' Wallace.

Bob's suggestion of the Jodo books rings true for me. There's a good Judo book...I think it's has Love and Judo in the title...dang can't remember, but I'll get back to you on the title. Anyway it has a pretty good breakdown of ukemi, kinetic impact, and the physics of the slap during a fall.

If anyone is interested, my analysis is turning out fairly well. My 'expert' (yondan, with really good ukemi) is using live-toe forward and backward rolls, my novice (experienced in ukemi X 6 hours over a two week period) has the classic corners where he should be round, and tries to turn to look as he does the backward roll.

Right now, we are looking into writing a separate program to flip the force, velocity, and acceleration data on the backward roll to see how truly close to 'the same thing just backwards' it is to the forward roll. Clearly, a more advanced study would require many people as everyone has a different morphology. My expert film, placed side-by-side, looks like one is watching the forward and reverse of the same roll (except that hanmi stance is wider in one).

Good luck on the physics!


"To educate a man in mind, and not in morals, is to educate a menace to society." ~Theodore Roosevelt
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Old 04-02-2003, 09:02 AM   #7
aikidoc
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I too recall an article like the one described by Jonathan. I'll dig in my archives and see if I kept it.
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Old 04-02-2003, 10:36 AM   #8
Veers
 
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I looked in Esquire and some science magazine...but can't for the life of me remember which science magazine it was, nor which of the two the article was in.

The early bird may get the worm, but the second mouse gets the cheese.
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Old 04-02-2003, 10:40 AM   #9
akiy
 
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I believe this is the article you're looking for:

Walker, Jearl. The Amateur Scientist: In Judo and Aikido Application of the Physics of Forces Makes the Weak Equal to the Strong. Scientific American, vol. 243, no. 1, pp. 150-161, July, 1980. (Illustrated commentary on the physics of torque and leverage.)

Hope that helps,

-- Jun

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Old 04-02-2003, 10:47 AM   #10
Veers
 
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*laughs* Impressive, Jun...

The early bird may get the worm, but the second mouse gets the cheese.
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Old 04-02-2003, 10:47 AM   #11
bob_stra
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Re: Re: Physics Biomechanics Aikido

Jane Tao wrote -[/quote]If anyone is interested

Hey, I'm standing right here,

dammit.

My 'expert' (yondan, with really good ukemi) is using live-toe

Wa huh? "Live toe forward" meaning...what exactly? Or is this a reference to RLA gait?

and tries to turn to look as he does the backward roll.

Wow...ok. So will there be a blindfold involved anytime soon?

(not that I got a thing for blindfolds. Well, ok, maybe a little...uh...nevermind)

side-by-side, looks like one is watching the forward and reverse of the same roll

Hey, that *is* interesting! Ohh, you could have fun with that little tidbit...maybe build a model...or do something with the cog. science guys re: neural nets. <drools>

Ahem. Anyhow, the book you were thinking of might be "For the Love of Judo". Though that's a kids book. Much better is the "Biomechanics of judo". Or anything by Geesink.

Another good place to look -

http://www.per.ualberta.ca/biomechanics/bwwframe.htm

And lots of articles to dig up from here...

http://isb.ri.ccf.org/biomch-l/archi...-11/00124.html

Coincidentally jane, for your amusement, I have a topic for this semester.

"The cybernetic nervous system - chiropractic as information theory".

It wordy AND pretentious at the same time. Whay!!

Last edited by bob_stra : 04-02-2003 at 10:51 AM.
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Old 04-02-2003, 12:26 PM   #12
Joe Jutsu
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There's a section in C.M. Shifflett's book "Aikido: Excersises for Teaching and Training" that I found quite helpful on this subject entitled "Aiki Traffic: Physics off the Mat" that makes some very interesting points regarding momentum, levers, gravity, and torque. It does not go into super detail, because the section is not long but there's lots of other physics throughout the book. It made a really interesting point about why it's so effective to be soft during a technique, stating that tensing up and trying to use strength gives ukemi a lever and the chance to throw you... anyway, I hope this has been somewhat helpful, and good luck on the project!

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Old 04-02-2003, 01:00 PM   #13
Choku Tsuki
 
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check out fightingarts.com

Quote:
Jun Akiyama (akiy) wrote:
I believe this is the article you're looking for:

Walker, Jearl. The Amateur Scientist: In Judo and Aikido Application of the Physics of Forces Makes the Weak Equal to the Strong. Scientific American, vol. 243, no. 1, pp. 150-161, July, 1980. (Illustrated commentary on the physics of torque and leverage.)
This article can be found here

--Chuck
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Old 04-02-2003, 06:27 PM   #14
ikkainogakusei
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Re: Re: Re: Physics Biomechanics Aikido

Quote:
Bob Strahinjevich (bob_stra) wrote:
Hey, I'm standing right here,

dammit.
Alright Bob, no worries, I'll fill you in. What else do you want to know. Hmmm... how 'bout the boring stuff that was a lot of work... took me two days just to digitize all the joint centers on my 'expert', alot of 'next frame'...<click>...'next frame'...<click> now I've got to work on the noise and perfect things like the acceleration data (that's where I find my mistakes the most)
Quote:
Bob Strahinjevich (bob_stra) wrote:
My 'expert' (yondan, with really good ukemi) is using live-toe

Wa huh? "Live toe forward" meaning...what exactly? Or is this a reference to RLA gait?
Okay, have you ever noticed that at the beginning of a back roll or the end of a forward roll that the 'rear' foot can either be dorsal side down('dead' toe) or plantar side down ('live' toe)?
Quote:
Bob Strahinjevich (bob_stra) wrote:
and tries to turn to look as he does the backward roll.

Wow...ok. So will there be a blindfold involved anytime soon?

(not that I got a thing for blindfolds. Well, ok, maybe a little...uh...nevermind)
No next time will involve force plates. No blindfolds Bob. It might be possible that a novice would still turn their head though, even blindfolded. If you think about it (theoretical) we don't learn to locomote by going in the direction of the center of our blind spot, nor is our vestibular system used to considering that curvilinear propulsion backwards is a good thing. We must train ourselves our of that hesitancy. At least that's what I've seen in all of the novices that come in each semester.
Quote:
Bob Strahinjevich (bob_stra) wrote:
side-by-side, looks like one is watching the forward and reverse of the same roll

Hey, that *is* interesting! Ohh, you could have fun with that little tidbit...maybe build a model...or do something with the cog. science guys re: neural nets. <drools>

-
Cog? Neural nets?
Quote:
Bob Strahinjevich (bob_stra) wrote:
Ahem. Anyhow, the book you were thinking of might be "For the Love of Judo". Though that's a kids book. Much better is the "Biomechanics of judo". Or anything by Geesink.
Well I may have somehow mixed the title, but I'm sure what I was looking at wasn't a kid's book, I'll have to look for it.
Quote:
Bob Strahinjevich (bob_stra) wrote:
Oh now that's ironic, I've been looking at UofA possibly for their doctoral program. But since I'd be an international student, I'd pay through the nose, and it snows for 4 months out of the year Brrrr!
Quote:
Bob Strahinjevich (bob_stra) wrote:
Coincidentally jane, for your amusement, I have a topic for this semester.

"The cybernetic nervous system - chiropractic as information theory".

It wordy AND pretentious at the same time. Whay!!
You're silly. Do you suppose pinched wires would be affected the same as pinched axons? So what's the hypothesis?


"To educate a man in mind, and not in morals, is to educate a menace to society." ~Theodore Roosevelt
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Old 04-02-2003, 10:26 PM   #15
bob_stra
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Re: Re: Re: Re: Physics Biomechanics Aikido

Jane Tao wrote

>Okay, have you ever noticed that >at the beginning of a back roll or >the end of a forward roll that the >'rear' foot can either be dorsal >side down('dead' toe) or plantar >side down ('live' toe)?

No. I just do my roll ;-)

Did you specifically recruit newbies with two left feet ;-)

>We must train ourselves our of >that hesitancy. At least that's >what I've seen in all of the >novices that come in each >semester.

Any tips for speeding that up? I'm still having troubles with my highfall ukemi.

>Cog? Neural nets?

One of our local uni's has a cognative science department that's heavy into the computer modelling of human movement. (the biomech and cog science guys share labs in 1st yr I think) Though I don't have any of the details ;-(

Focus on building expert systems and such. It would be cool to create a "ukemi expert system" and see how it develops.

>Oh now that's ironic, I've been >looking at UofA possibly for their >doctoral program.

The wheather here is much kinder. The fees are less. And also, there's lots of good aikido about.

http://www.uwa.edu.au/

http://www.hmes.uwa.edu.au/

>You're silly. Do you suppose >pinched wires would be affected >the same as pinched axons?

Troll. You *know* that axons don't pinch ;-)

No, more of an "information gone askew" thing. Like, why do people get idiopathic scoliosis...yadda yadda. Just started it, not sure which direction to go in yet.
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Old 04-07-2003, 12:25 PM   #16
aikidoc
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There also may be some connection with the bucky ball concept-tensegrity: tetrahedrons (triangles), sphere(circle), cube (square). These geometric shapes have an impact on forces and structural stability.
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Old 04-07-2003, 02:16 PM   #17
ikkainogakusei
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Re: Re: Re: Re: Re: Physics Biomechanics Aikido

Quote:
Bob Strahinjevich (bob_stra) wrote:
Any tips for speeding that up? I'm still having troubles with my highfall ukemi.
Hesitancy, or force production for the high falls?
Quote:
Bob Strahinjevich (bob_stra) wrote:
>Cog? Neural nets?

One of our local uni's has a cognative science department that's heavy into the computer modelling of human movement. (the biomech and cog science guys share labs in 1st yr I think) Though I don't have any of the details ;-( Focus on building expert systems and such. It would be cool to create a "ukemi expert system" and see how it develops.
Oh, Cog meaning cognitive...cool. Sure, if you're implying that there is also some self-evolving artificial intelligence, that would be interesting, especially if we modified morphology, but kept the learning curve the same to see what happened.
Quote:
Bob Strahinjevich (bob_stra) wrote:
The wheather here is much kinder. The fees are less. And also, there's lots of good aikido about.
Yeah, I've seen some pretty amazing pics of the countryside there, I've got quite a few family members who spent some time in Australia. I must say, I fell in love with Banff and the Canadian Rockies though. I'm a high mountain with snow and big bears kinda gal. California seems to have gotten rid of all of its doctoral programs so the in-state tuition is out the window, but if I go out of state I may as well go out of country and Canada has a slight edge on Australia for currency.

As for aikido, what would you say is the predominant sub-style there? (Ki-scty, Yoshinkan, Tomiki)
Quote:
Bob Strahinjevich (bob_stra) wrote:
>You're silly. Do you suppose >pinched wires would be affected >the same as pinched axons?

Troll. You *know* that axons don't pinch ;-)
Ouch, have you ever known me to give you hanging rope Bob? Naw, I figured we've got mutual respect going.
Quote:
Bob Strahinjevich (bob_stra) wrote:
No, more of an "information gone askew" thing. Like, why do people get idiopathic scoliosis...yadda yadda. Just started it, not sure which direction to go in yet.
Kay so I've got questions for that. Is it binomial info gone askew? (the ol one zero, excitatory and inhibitory action potential) Or is it realted to affect of spinal grey matter (interneurons, etc)? What (from the chiropractic perspective) will you be addressing?


"To educate a man in mind, and not in morals, is to educate a menace to society." ~Theodore Roosevelt
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Old 04-07-2003, 02:18 PM   #18
ikkainogakusei
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eh, off topic correction on the currency

I got it mixed up, Aut has the edge on Canada. oops.

"To educate a man in mind, and not in morals, is to educate a menace to society." ~Theodore Roosevelt
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Old 04-08-2003, 02:54 AM   #19
bob_stra
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Too many Re:'s

Jane Tao wrote

>Hesitancy, or force production for the >high falls?

Hesitancy.

>Oh, Cog meaning cognitive...cool. Sure, >if you're implying that there is also >some self-evolving artificial

That's exactly where I'm going with it ;-)

>As for aikido, what would you say is >the predominant sub-style there? (Ki->scty, Yoshinkan, Tomiki)

Hard to say. The club I train at is probably the biggest (yoseikan), followed by Ki society, then Tomiki. Though there are others (even a few aiki-jitsu folks). For a city of barely 2 million, we sure got a lot (8-10) aikido clubs.

>Ouch, have you ever known me to give >you hanging rope Bob?

I'm nothing if not playfull ;-)

>Kay so I've got questions for that. Is >it binomial info gone askew?

I'm still trying to figure that out. As far as I can see (from lit. reviwes) there isn't anything actually "bad" about idiopathic scoliosis. Sure, some slight increase in back pain. And complications if it goes too far.

I'm starting to wonder if its just a normal variation. Logically, a laterally curved spine should be even stronget than the normal design.

>What (from the chiropractic >perspective) will you be addressing?

Musculoskeletal components. Treatment.

Is treatment even necessary? Inhibition vs open ended info exchange.

(still just getting into it, so my ideas aren't totally formulated yet)
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