[goaty]

This looks like the easiest way to get your muscles done,    Its a simple attachment of "ropes" to a hollow inside, and you need elastic/bellows/bags to allow for the translation to rotation that's going to happen.

[HS]

That's really good! I will copy if you don't mind..

[goaty]

Id love it if you did!      Yes! it looks attractively simple!   I like it too!   Its in the "soft robots" class, of body designs.   nifty.
I knew I was onto something when I splayed out the connections to the joints,  seemed like the right way to do it.

But the system isn't quite finished.  I just put it into the computer, and it looks like its not stable enough.  and the diagram is missing an important element, it needs a round obstructor I think, so it obeys a rotation when you pull on the pulleys.

The "bags" are the equivalent of a ball joint  (and just for trivia, they were used in old school cameras ages ago,  but we are using them as a joint here .)
and I don't think the tendons are going to able to hold it tought properly...   ill be back if I come up with the solution.

It really needs someone to go craft it in real life then the problem&solution will be more obvious. 

Sure looks easier than hydraulics  doesn't it,  even tho you can put water bags into it, and its basicly the same idea,  except we just got rid of the water.

[goaty]

Hey HopeFullySomething->
I fixed my problem,   you make it one string against a bearing that is on the rotated rigid next piece.   so you pull either way, and the bag will stretch with the pully string.

If you were getting exorbitant, youd put a roller where the bearing is,  but what if there isn't enough time? 

[HS]

Cool, I like it! I'll just need to figure out how the springly part will function. Maybe it doesn't need to be springy, just flexible. Needs to be able to bend but at the same time resist contraction.

[goaty]

Be my guest if you want to try and implement it,    remember theres no warranty if it ends up causing you misery.    btw, just use a tshirt or whatever for it, don't need no flex d00d.

Me myself lately im imagining a cool little thing made of voxels for it, make it extra easy... stiff voxel, cloth voxel, stiff voxel, cloth voxel, chuck some ropes in.  potato potato  ;0

[HS]

Alright, my quadruped "Blinky" creature needs some sort of legs, and I've got a lot of spare shirts. This should be interesting. 

[goaty]

Alright, my quadruped "Blinky" creature needs some sort of legs, and I've got a lot of spare shirts. This should be interesting. 

Youd be a total star if you did.

The shirts have to support the weight of the bot,  so maybe youd need a few layers,  or the rope will rip them.   Interesting to see what u come up with,  but if u end up not wanting to bother, flake out I don't mind I should be the one proving my own designs after all.

[goaty]

I thought some more, and I think that you don't attach on the bellow, you attach just after it, and u need to get the length between it and the bracing right, to give it the play it needs.  and the bags have to start off with a bit of compression on both sides so it adds up.

[HS]

The main physics of the design are good. The wide structure resists breaking/bending and protects the moving parts inside it. I'll probably have to go through many many itterations to get the details right. If anything ends up  working i'll post on my project thread.

[goaty]

np.    I should be putting this together myself.  just cut in so many directions for this bot im doing.   physics engine, computer vision, body muscles(this) power source, input and output, then the computer, then manufacturing, and a senile idea to get infinite processing power, etc etc.   I can only do one thing at a time, but usually just wasting time on youtube, just to make it all grind to a halt.

Nope, design not working,  There needs to be an obstructor of some kind, to keep the joint always the same length no matter where its pointing,  also springs/flex could be used here...



Heres my computer simulation of it,  with a voxel creature maker - the magenta cubes are the elastic ones, and the cyan ones are the rigid, and they have pointy ends to touch the surface with, because I think this might make it easier to get going with at first.  bit more to fix before I get to see it go,  but theres a few things about physical walking that I have to work out yet...

[HS]

Found it! Was trying to design this from memory and it wasn't quite right...

[goaty]

Cool!     id feel the love if you prototyped something like this for me,  cause I don't know if its going to work or not, its all just pictures in my head still.


</img>

Its not a complicated thing,  you should put a spin on it,  but how I see it - its all pretty much easy to understand except there needs to be an obstructor rod which is going to sit against a rotating plane to cause a rotation when it spins.

This design is cool to me,  cause you could probably 1 hit cast it with whatever material and it could miniaturize really well even to the size of a 2c piece.

The thing not in the explanation here is of course how to add the linear drives which pull on the tendons, and how to pass the power from the battery through the computer to set their positions.    You can use electric or pneumatic, and i'm such a dodgy bastard id say its better off without gears or spoolies, they just complicate matters.

Theres actually another roboter on the internet who made a beautiful pully wire worm, and he hates gears in em too   you can join the club if you want.

[Korrelan]

https://pdfs.semanticscholar.org/3396/e17daf570f966ef7722446ea3e7ea7a52a75.pdf

 

[HS]

there needs to be an obstructor rod which is going to sit against a rotating plane to cause a rotation when it spins.

So it will have to hold the weight of the robot? Is it 3d like a ball and socket, or 2d like a hinge?

The thing not in the explanation here is of course how to add the linear drives which pull on the tendons, and how to pass the power from the battery through the computer to set their positions.    You can use electric or pneumatic, and i'm such a dodgy bastard id say its better off without gears or spoolies, they just complicate matters.

The cheapest might be regular electric motors pulling string on a stick, like a puppeteer. Hehe I feel the same way about valves, I went out of my way to design a valveless steam engine one summer. It would need to be really big and heavy to work though.

Theres actually another roboter on the internet who made a beautiful pully wire worm, and he hates gears in em too   you can join the club if you want.

Yeah, that type of thing is really fragile. (gears, valves, bearings) Needs to be exactly right or it stops working. Not the type of thing that can wander around on an alien planet for a hundred years, (as things should). 
Something that has loose tolerances, which can take damage but keep working, that's how I envision the best machines.