chapelier fou

I am trying to model the movement of a swing (or pendulum). I'm struggling to approximate the acceleration (towards the lowest point) and deceleration (towards the highest points). 

Could someone help with this ? It doesn't need to be 100% accurate / realistic. 

Here's a (linear) basis to be expanded : 

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Hi there, 
I am trying to model the movement of a swing (or pendulum). I'm struggling to approximate the acceleration (towards the lowest point) and deceleration (towards the highest points). 
Could someone help with this ? It doesn't need to be 100% accurate / realistic. 
Here's a (linear) basis to be expanded : 


Hi there, 
I am trying to model the movement of a swing (or pendulum). I'm struggling to approximate the acceleration (towards the lowest po

modelling-a-swing

Went another route, with [cycle~]. Seems closer to reality. Any better idea ? How would you change the "gravity" here ? 

i'm not fast/smart enough to incorporate true 'gravity' (acceleration of 9.80665 m/(s^2)), but it would involve something like changing the speed of cycle~ along with the amplitude all at once:

(if you don't need this to work in the signal realm, you can also try 'sin' or 'cos' object instead of cycle~(will need to translate from radians based on π)... a pendulum is much like an object moving in a circle (except squeezed into extreme elliptical shape by being weighted towards one dimension)... for any circular motion, x and y positioning can be translated through cos and sin (but only use one of them for a straight swing along one direction)... might even be easiest if you use the non-signal version of 'gen' then you can just use the 'cycle' object there, but still work outside the signal realm)

I don't think it's true, as in a pendulum, the period of oscillation remains constant regardless of the amplitude of the movement. Or........maybe I'm wrong ? That looks so simple, but hey, I should have been a better student at school.

no prob, answer withdrawn(gravity will weight it towards 0 movement, was all i was trying to say, if you think about how that can work, i'm sure you'll come up with your own way) 

no prob, answer withdrawn(gravity will weight it towards 0 movement, was all i was trying to say, if you think about how that can work, i'm sure you'll come up with your own way) 
best.

Ouch ! I didn't mean to sound rude at all ! (did I ?) Especially since my brain really gets stuck when trying to understand physical phenomenons. 

Your answer was totally helpful and actually gave me hints for other stuff, you shouldn't have withdrawed it. 

Also you're right, no need to use [cycle~] when converting back to events.

Ouch ! I didn't mean to sound rude at all ! (did I ?) Especially since my brain really gets stuck when trying to understand physical phenomenons. 
Your answer was totally helpful and actually gave me hints for other stuff, you shouldn't have withdrawed it. 
Also you're right, no need to use [cycle~] when converting back to events.

in fact a quantum pendulum even behaves stochastic when the speed of its center is a constant.

for non-mathematicans such as me it is always a bit a mystery that you run a simple arithmetic algorithm/generator but whos result is unpredictable.^^


in fact a quantum pendulum even behaves stochastic  when the speed of its center is a constant.

@Chapelier: no worries at all, i didn't mean my response in any reactionary way: you helped me realize i gave too quick an answer, so was trying to back out quickly 😅

much respect. hopefully it's ok to withdraw answers, too: sometimes i'm quite incoherent when busy with other things, i don't always realize it until late/already-given(my patch was guessing as to a possibility of controlling how the distance from center and speed might change...but unfortunately, hooked them up together tandemly, when they might be individually controlled or perhaps have an inverse relationship... i didn't have time to think it through)

in any case, bumping this up for others to chime in. apologies i have to back out so quickly. wishing you all the best in finding a good suitable answer for this case.

@Chapelier: no worries at all, i didn't mean my response in any reactionary way: you helped me realize i gave too quick an answer, so was trying to back out quickly 😅
much respect. hopefully it's ok to withdraw answers, too: sometimes i'm quite incoherent when busy with other things, i don't always realize it until late/already-given(my patch was guessing as to a possibility of controlling how the distance from center and speed might change...but unfortunately, hooked them up together tandemly, when they might be individually controlled or perhaps have an inverse relationship... i didn't have time to think it through)

in any case, bumping this up for others to chime in. apologies i have to back out so quickly. wishing you all the best in finding a good suitable answer for this case.

Here's a pendulum simulation using the physics engine in jit.phys.world. It may be overkill for your needs, but once you have a simulation like this you can easily produce a range of behaviors by changing high-level parameters like gravity, mass, force, etc.

Thanks very much for this. Interesting ! 

I need to check deeper, but I can't find a way to disable friction (so the swing never rests).

Thanks very much for this. Interesting ! 
I need to check deeper, but I can't find a way to disable friction (so the swing never rests). 

Good point. I tried disabling forces including damping for the jit.phys.body and springdamp_ang and springdamp_lin for the jit.phys.6dof but the pendulum still came to rest. Maybe a Jitter guru can come to the rescue.

wat? are you sure? been watching this thing for awhile now, it never seems to come to rest with those settings all turned down to 0 😆

(i hope y'all don't mind... gonna steal this idea, been dreaming of a physics based 'perpetual motion'-machine sequencer for awhile (i even suggested the master to do a video on it so i could learn from them: 

https://cycling74.com/forums/create-music-and-visuals-with-maxmspjitter

 ...), now i see with the damp values how it can be done... i'll try not to use a strict pendulum-like setup, though 😇)

(i hope y'all don't mind... gonna steal this idea, been dreaming of a physics based 'perpetual motion'-machine sequencer for awhile (i even suggested the master to do a video on it so i could learn from them: https://cycling74.com/forums/create-music-and-visuals-with-maxmspjitter ...), now i see with the damp values how it can be done... i'll try not to use a strict pendulum-like setup, though 😇)

oh wait, i see how it comes to rest... i think you have to set gravity to 0 as well for everything to keep going(?)

(also trying negative values for some of the damping and friction... not sure what that does yet, though)

oh wait, i see how it comes to rest... i think you have to set gravity to 0 as well for everything to keep going(?)
(also trying negative values for some of the damping and friction... not sure what that does yet, though)


Also, I can't find a way to access to values like the Z angle. My goal is not to render the swing, but rather to use its position to drive something else. 

Also, I can't find a way to access to values like the Z angle. My goal is not to render the swing, but rather to use its position to drive something else. 
(but I'm happy with the [cycle~] way). 

You can send 'getposition' to jit.phys.body to access position data out of the left outlet.

modelling a swing