[theory] Anti-Spin

Hi there,
I worte a text about anti-spin, you might be interested ^^

here is a english version :

Anti-Spin theory

Please, be tolerant, there must be a lot of mistakes as I don't really know how to translate and so on so I need you to know what's good and what has to be changed...
Comment here, critics are welcome Wink

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you are so inspiring, thank you!

i´m sur, you will have fun with this one:
http://did.mat.uni-bayreuth.de/geonet/beispiele/bernoulli/allgZykloiden/allgzykloiden.html

dont´t matter with the language. i also don´t understand the text ;(

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logic can get you from A to B - imagination will take you anywhere
visit - www.light-motion.net

!!!!! SUUUUUUUUUUUGOOOOi !!!!! I just love it !!! Very Happy

Thanks YOU !!!! Gé !! Very Happy

that's a greeeat virtual Toy Razz

to play with!!

that's reminds me the game I used to enjoy by drawing circles like this :

Here is some others pictures I took of Pich anti-spin draws at ENS.

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I knew!

in fact you are the first firedancer who likes this feature, the others I showed it were just: Rolling Eyes

lets get geometrical. Cool

some terms:

the line on which the center of a rotation (in our case the hand) is moving is called evolute. in your text it is the grand circle, or the green line in the pics.

the originated figure is not a circle but a cycloid (I love this term, sounds like an ancient adventure)
in case of spin it is an epicycloid.
in case of antispin a hypocycloid.

imo, the draw of the cycloid is variated by:
- the relation of the diameter of the evolute and the diameter of the rotation (if you isolate its not a constant relation)
- the relation of the speed of the rotation and the speed of the center point on the evolute (constant or not?)
- the form of the evolute
- the position of the isolation points on the evolute (f.e. make a 3 branches star with a staff (therefor the evolute has to be a triangle) and don´t locate the isolation points in the corners, but in the middles of the lines. that result is the figure the pinky-end of yous staffs does)

I believe that it is possible to make a flower with a staff, if the evolute is a circle.
I believe that it is possible to make a star with poi, if the evolute is a triangle (I expect one would need short chains, heavy heads and high speed)

good night,

gé

_________________
logic can get you from A to B - imagination will take you anywhere
visit - www.light-motion.net

GREEEEEEEAT Very Happy

I'll read this two or tree more times and comment Wink

Cool I've find a cycloid friend (love this term also, I see just what you meen Wink

)

and with Pich that's make tree of us !! let's built an anti-spin community Cool

I think Nick Woosley is one of us maybe the GURU Shocked

lol here envryone is a spycho of circles Twisted Evil

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couldn´t sleep half of the night spinning thoughts about spins Rolling Eyes

another funny tool:
www.spherculism.com/help/poibot_009.html

I´m sorry I lost your postal adress, but I´d like to send you a cd with some animations with figures a rendered. otherwise I can send you by email, they take 13mb...

_________________
logic can get you from A to B - imagination will take you anywhere
visit - www.light-motion.net

YEEAH

great, thanks you Gé for this precious links ! Very Happy

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hey, I draw some pics Very Happy

http://www.firesouls.de/wbboard/thread.php?threadid=965

_________________
logic can get you from A to B - imagination will take you anywhere
visit - www.light-motion.net

what to say? flash is fun! =D

_________________
logic can get you from A to B - imagination will take you anywhere
visit - www.light-motion.net

Inscrit le: 24 Sep 2005 Messages: 2805 Localisation: Paris 13

This is hypnotazing ...

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"Your behavior is not funny and is wasting the time of the federal government."

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Faire de l'instant un moment intemporel, la faille spatiotemporelle.

sascha had also a dream about antispin with double staffs, and made it real the next day Very Happy

_________________
logic can get you from A to B - imagination will take you anywhere
visit - www.light-motion.net

Inscrit le: 08 Sep 2004 Messages: 62 Localisation: Ile de la Réunion

I don't understand why the two circles (the yellow one and the red one) are different ...
When looking at the animated staff, I see the yellow ball moving almost inside the yellow circle. At the opposite, the red ball moves almost outside the red circle. I would have drawn two similar circles (i mean ovals), whith a shape like the red one. Isn't it ?

Flash is really a great technology for such educative videos !
thank you gé !

I would like to add ima's citations and pics, and flash video as Gé did, in the Encyclopedie du Swing, what do you think about this ? do you agree ?

hi talaron,

you are right the drawings of the figures are not 100% correct, cause I made am by hand.

for understanding:

the green line is the path of the hand. (in terms of geometry this line is the evolute and the generated figures are cycloids)
the blue circles have the diameter of the staff. they are only for orientation. I placed a circle on every corner and on every middle between the corners, so at all 6 circles.

the red and the yellow lines are the paths of the heads.
the yellow head allways points outwards at the moment when the hand is reaching a corner of the green line
the red head is pointing outwards at the moment the hand is reaching the middle between two corners. (this point is closer to the middle of the triangle than the corner)

the yellow and the red figur would have the same shape if the green line would be a circle.

_________________
logic can get you from A to B - imagination will take you anywhere
visit - www.light-motion.net

sorry for the mess with the colors Laughing

the blue circles are placed on the corners of the triangle
the pink ones on the middles

the yellow head is pointing outwards, when the hand is at a corner of the triangle. at this time he must be on the blue circle
when the hand is reaching the middle between two corners, the yellow head is pointing inwards, touching the pink circle.

it´s strange how different the same figur looks when the diameters are changed...

_________________
logic can get you from A to B - imagination will take you anywhere
visit - www.light-motion.net

Inscrit le: 08 Sep 2004 Messages: 62 Localisation: Ile de la Réunion

YES!
this pict is perfect!

to see how they're moving in space with an animated version would be great Wink

here you are! ;P

_________________
logic can get you from A to B - imagination will take you anywhere
visit - www.light-motion.net

Wouaaa ... Shocked

That's perfect Surprised

thank you so much !!!

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AWESOME Gé Very Happy

now you're qualified for programming flash based 2D mechanical engineering software Laughing

so to say it quicker, and according to your animation:
- move the middle of the staff on a triangle,
- one revolution of the staff by triangle side

degrees of freedom to control the damned thing:
- orientation of the triangle (vs gravity)
- speed of rotation of the staff ( what you fingerspin )
- speed of travel of your hand (what you slide / translate )

next question:
There is a relation between the two latter, isn't it? At least to have a good looking geometrical pattern.
I mean, I guess the overall pattern wouldn't look as good, if these two speeds are not in proportional relation to each others'

From a practical point of view:
this is how I control my two staff to make antispin flowa (in general, not only for your drawing)
1. start up the system by making the staffs spin (ie set an initial rotational speed by fingerspin = the normal spin)
2. then control only by travel-speed/position of the hand

So how do I do step 2:

if the staff is inclined vs. the sliding direction, and if you quickly push or pull (ie the translation / sliding), this will make the staff rotates ! Rolling Eyes

The created rotation is maximum when the staff is inclined 45° vs the direction of sliding. Gravity wiill add/substract some forces, to highlight this, let us consider different positions:
- sliding direction is vertical (along gravity): incline the staff 45° vs gravity, and move your hand up & down (of course the staff will accelerate more when you slide down due to gravity)
- sliding direction is horizontal: incline the staff 45° vs horizontal (or gravity ) and slide your hand forward and backward (the upper part of your green triangle)
- sliding direction is inclined 45° vs. gravity: start with the staff horizontal (therefore beeing inclined 45° vs sliding direction) and accelerate it along the inclined direction

purpose of this method:
- that one reach proportionality between the 2 speeds (these 2 parameters will therefore be coupled)
- that one only do slides
Moreover, controlling only one parameter (the slides) will make it easier to
- drive the staff
- keep the two staff parallel (same as with poi when you do isolated antispin flowa, and try to keep the two poi split-time)

How do you guys do yours?

next step:
to train to slide your hands on two angularly-offseted triangles, in order to reach the 6 edges Jewish star

Note:

it's easier to fingerspin in antispin than in normal spin:
the inertia of rotation (centripetal forces/accelaration) will keep the staff in contact to your fingers in antispin, whereas in normal spin, the staff will try to go away from your fingers (ie drop). Moreover the contact forces to your fingers will be lower (less painful)

the staff will accelerate more easily if you fingerspin offseted from the center (hold the staff not on the middlepoint). When you do this, the contact forces between your fingers and the staff will - unfortunately - be proportionnaly increased (it hurts)
This mean the above practical description is not completely true, as when one fingerspin the center of rotation is moving a little bit around the center of the staff. Anyway "sliding only" is my purpose, I'm still compensating a bit by fingerspin in order to counteract the above problem, which creates some "hard points" ! (also depends on how many fingers you're using ... 3 is enougth I believe)

to do step 2 properly you need to control sliding acceleration (negative or positive, both will make the staff spins). So don't forget to brake !!

ps: I'm only talking about double staff (single doesn't interest me)
it's easier to explain this in the Real world

Have skimmed juliens AMAZING anti-spin document! Shocked

It's soooo good!

One thing I have been playing with is to do half a circle (with your arm) anti-spin and the other half as a isolation of one end of the staff. But you reverse the direction of the staff so that your arm continues on it's circle. You can do a lot with this sort of thing.

I like to think of anti-spin in terms of the center of rotation of the staff. And all isolation and anti-spin and longarm stuff follows from this.

Maybe I will go draw things now.

THANKS!