Hey, everyone!
I’m looking for a help with folding a triangulated geometry. There is an issue when I try to fold the origami worm, it doesn’t fold completely and eventually returns to its original state. Could you please help me to figure out how to solve this problem?
Filipp_Origami_foldingProblem.gh (7.6 KB)
Filipp_Origami_problem.3dm (116.5 KB)
Eventually, it is suppose to look like in the attached image-reference.
Thank you for your time!
Where you took that reference from?
You need cuts in your origami, otherwise that’s a rigid structure and can’t fold.
Edit: i think that picture reference is completely wrong.
Wow, could you please tell me why the reference is wrong? I used it from a scientific article.
By the way, could you please also tell me if u maybe know how can I built magnets (in tail, middle and front sides of the origami-worm) that affects each other in origami-worm?
Because I tried that pattern of triangles with kangaroo, and it do not bend as in your picture. At all.
The best you can do is to make a flat rectangular grid with diagonals but removing the black fold lines (Looking at your picture, the flat version at top left), resulting in something similar to “Miura” type.
But that type start flat and keep being flat while folding. (it keeps a planar global shape)
Or you can look for the " Yoshimura" type
which start flat, then is a open cylinder half-fold, and is a virtually 0-thick circle/arc when fully-fold.
Then, sorry if I laugh. 
The case are two: either that article is wrong, or that picture alone is not enough to explain what the article is really describing. You choose.
Does that article really describe this as “origami” and that it have no stretching/compression of the segments???
(“Origami” usually means little-to-none deformations…)
13.76 green camping chairs. (made with recycled plastic)
Seriously magnets works really bad for this. But this is a personaly opinion.
Magnet works with the inverse square distance rule, meaning good at short distance and 0 strength at big distance. Exponential. Difficult to calibrate the field intensity to regulate the resulting distance. Probably end up to a “on-off” situation, with no in-between positions…
You might have more luck with a mechanical force or by using pneumatic.
Look at the bellows of the accordion instruments… you should find something.
Also, often origamis DO have some deformations. Paper is elastic!
Many video tutorials with paper and glue end up relying heavily on deformations to achieve shapes.
Even the bellows likely have deformations.
Using a simulation tool to do this, either you know there are deformation or know there aren’t.
What is the case?
Without deformation, the picture you posted is a rigid structure.
This is my opinion.
@DanielPiker can I ask for your opinion here?
I’d like to be corrected if I’m saying stupid things…
A truss structure:
your scientific picture:
(which is even more rigid due to more segments…
Should we fear all structure around the world are about to collapse into an origami?
… or maybe that scientific article is also talking about shrinking/stretching of red/blue segments?
This rely on deformations, shearings:
Also study this:
I see, and firstly, thank you for those variations of folding the origami. I believe Yoshimura technique is better.
Well, I can say the whole article is about how this worm-origami can be useful in real-life by using dipole magnets in order to move it.
You are right, this little-guy-worm-origami is supposed to stretch and deform, but only when the main bar magnet is taking closer and closer to the disk magnets inside the worm-origami. If you would like to read it, I attach the the pdf version for this doc:
Multiphysics_Simulation_of_Magnetically_Actuated_Robotic_Origami_Worms (2).pdf (3.2 MB)
Okaay, then I won’t use exactly magnets, but still:
I would like to ask you a question about magnets: is there a way to tie disc magnets to the inside of origami (which are inside, in the middle and in front, as in the reference)?
Or it would be better to just create anchor points in the same places (in tail side, in the middle, and in front), then create a curve that somehow needs to be tied to the entire origami worm, for deformation and folding at the same time: so that the entire structure can bend. And then use the main bar magnet to act vertically on these disc magnets, so that when I lift it closer and closer, the discs will start to rise at the same time depending on the position of the main bar magnet?
Hahaha!
Yess, you’r are right, it should stretch!
You’re right - closed tubes can never collapse without some stretching of the panels, as that would violate the Bellows conjecture.
We call it rigid origami when the individual panels do not deform, and all the edge lengths stay the same, only the fold angles change.
These collapsing tubes are an example of elastic (i.e. non rigid) origami. The amount of stretching can be very small, but is essential for it to work. The pop-through behaviour is a giveaway that a folding pattern is relying on elasticity.
A previous discussion with an example of this pop-through:
Sometimes the paper moves between 2 states where the panels are unstretched, but it has to go through a stretched state along the way, so as you push it over that energy hill it wants to settle on one side.
You should have attacched it in the first post…
btw, in that paper we can see Rhino and they are mentioning the “Hinge” kangaroo goal… XD
As for the Kangaroo goal: Does it mean I need to deal with hinge mainly? Could you please help me how can I do so? Unfortunately, I didn’t manage to find a proper tutorial for this on YouTube
Got this!
Thank you very much for sharing the post and letting me know that this is another sort of origami folding: rigid origami. I will use this way to build the worm-origami !!!
I’m sorry for that… Next time I will attach full versions for the docs after all
Sometimes a real world experiment reveals more than a simulation.
The scientific paper is correct: using a sheet of paper, that form definitely can be folded:
Most paper is actually pretty inelastic so it isn’t good at stretching. What it is good at is bending and if you try to fold the paper model you will find that a lot of bending is both essential and sufficient.
@DanielPiker, would Kangaroo be able to simulate this if the panels were significantly subdivided to allow bending?
Regards
Jeremy
Thank you Jeremy!
you mean that is a pseudo-cylinder, and you can fold and un-fold it freely?
I can’t believe it is working without significant deformation.
This evening i’ll try too with real paper.
I wouldn’t say freely… You have to coerce the various folds to come together reasonably simultaneous on the three sides. It would probably be easier if you were an octopus. It should help to pre-fold the creases in before sellotaping the ends together (unfortunately I taped mine inside out so every crease wanted to go in the wrong direction!)
Indeed, paper won’t stretch a very visible amount, but I’m pretty sure it really does have to stretch for this particular pattern to work, not just bend.
We could break down non-rigid origami further into isometric and non-isometric deformations. An example of an isometric deformation would be rolling a sheet into a cylinder.
It will behave quite differently depending how the sides are joined together If it’s just closed loosely with tape then the deformation can easily be taken up by the shape opening up slightly along the seam. I think if you glued it securely it would be more apparent that it has to push through that deformation in order to fold.
Watch out that you don’t make the paper strip too wide: I used half a sheet of A4, 297mm x 105mm, and when folded the diagonal creases cross near the centre with only 5-6mm clearance.
I’m sorry to ask you again, but this is really important to me: do u have guys, by any chance, any relevant sources or tutorials that explains “Hinge” component for Kangaroo?
