Automata Mechanism
stu sutcliffe
Posts: 274
Just wonderin' , has any one made any sort of mechanism using bullet physics? Nothing too complicated just your basic camshaft /crank sort of stuff?
I was looking at the other thread about the Pepakura software, then started to think about how cool it would be to make a paper automata . Design it using Carrara and see if it works.Then print it out and make one...a sort of poor mans 3d printer!
"What could possibly go wrong..."
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Hey stu, well this isnt carrara but I stumbled upon this t'other day.
Could be of interest:
Check out the program called Phun - see a vidwo 2/3rd down page http://guru2.karakasa.com/top_e.html
He appears to use this program to make clocks from paper?
http://guru2.karakasa.com/PCP_menu_e.html
direct link to the Phun youtuve video http://www.youtube.com/watch?v=HEhGmidabh0&feature=player_embedded
I got to the chaps site because he'd made models of Bosch charactres in 3d, Bosch being a favourite painter of mine
Thanks for that ! That program looks ...er fun! I will have a play with it when my flu has gone away ....
Here is a website you may or may not know http://www.boschbruegel.com/ . A friend of mine Colin Batty contributes to it. ( Colin should be more well known than he actually is he is a brilliant painter and an even more brilliant sculptor! You have probably seen his work but have never heard of him!)
Stu,
I've been trying to do similar things using bullet physics in Carrara and have come to the conclusion that it cannot be done.
The problem, as I see it, is that any machine that you build will need some keyframe animation to make its parts move. However, Carrara's keyframe and physics motion methods don't interact properly, usually resulting in parts passing through each other rather than contacting.
The best I've been able to build is a pendulum, since it required no keyframed motion.
I have had a little go and it seems not too bad for me! I made a basic piston and cam. The cam had a rotate modifier so like you say that probably does not count as keyframing maybe, but it worked ok. I know what you mean about stuff passing through . I gave up on a swinging chain I was trying a couple of years ago, I thought that might have been sorted by now.
One thing I did try was using that "chain falling down stairs preset" that comes with carrara. I found if you make the first link keyframable you can animate it quite slowly and it will all stay intact but if you do a really sharp move it passes through itself.
For myself the rotate modifier is ok for automata because basically that is how they operate . But hey it was just a mad idea anyway, I think doing what flashed into my brain in an instant would be a heck of a lot of work.....and I'm really lazy!!
Maybe I will have further experiments and see if I can make one of those "flying pig" type automata.....just in carrara....and see how far I can get before I start bashing my forhead with my palm....
I found a big help was to turn the friction to zero
Edit : I ve just been playing around with a couple of hoops ,one being keyframed ,when i moved No 1 hoop around on an horiz plane it seemed ok but up or down it comes apart. There is a physics tab in the scene tab, that I cant quite remember using before,but I set the fidelity to 100 and the simulation to 1000 percent (?) and I couldnt shake them apart! Progress I guess.
Very cool report! Can you make me a paper clock too? That would be sweet!
Say Stu, do you use Carrara at all in the creation of those figures you sculpt in 3d Coat? Like your Boris and stuff?
I've been building more stuff than I care to lately (I'd far rather just animate my scene and render), and I've been finding Carrara to model really easily. I certainly feel more adept at modeling in Carrara than Hexagon - though I like that too.
No paper clocks from me I,m afraid!
I used to block out stuff in Carrara for use in 3dcoat, I made a couple of posable "mannequins" a man and a laydee. I could just as easily used a daz figure, but in my head that was cheating! I still use Carrara to do the hair and eyes, and I render. I would use Carrara for technical objects. I like its modeller, but it could do with improving a bit, but its fine for me. I havent run Hex for simply ages and Ive sort of forgotten about it. But it does have its uses. But 3dcoat is great, I dont think it is quite up to zbrush, but I cant make sense of Z....too many buttons . 3dCoat I find quite manageble and Andrew who owns and runs the company is a true gent! What Carrara is to Maya ,3dcoat is to Zbrush.
ps I got 12 hoops all swinging from a keyframed hoop. Next stop keyframe the last hoop as well . and see if that stays together and perhaps add a few more hoops, If Carrara can handle all that it should be able to make a flying pig with about 6 moving parts easily!
Hi Stu:)
Glad you brought this up - I've been trying to get something similar going for ages so as animate a steam locomotive I made some time ago.
Here's a quick video showing the problem - no physics or keyframing, just a wheel with a spin modifier. All in a hierachcy , with the conrod and piston pointing at a target helper object directly above.
All works well, excepting that the piston and conrod spontaneously rotate in the X and Z axes and nothing I can do will prevent that. I get exactly the same using angles or quarternions. The THO doesn't move.
http://youtu.be/VGadnp-95Tc
thanks stu, great site, your friend Batty makes similar images stylistically to yourself, I see. :)
Hya Roy, does sparrohawke have a linkage plugin?
hmm his site seems to be down :(
Hi head wax
I seem to remember something like that - I have all his plugins stored somewhere - will have to take a look:)
Just been looking at DCG - he has Cognito which should do the trick. But for something that appears to be so basic, I don't think the expense is justified.
well considering Ensonique originally scripted these in anim8or,.... but he doesn't say how he transferred the first one to carrara?
he might have used sparrowhawkes plugin?
https://www.youtube.com/watch?v=i8PxEIdquQU
Stu, this is what we expect from you when you get a handle on the physics
https://www.youtube.com/watch?v=3BXZXImAV1Q :)
He - I remember the beer bottle opener - all done in Anim8or, which has far less amenities than Carrara - he's really good at this:)
Found my stored Sparrowhawke plugins - all for C7, which I no longer have. No linkages plugin amongst them, though.
Had a few more tries - putting constraints on the conrod keeps it from rotating, but then it ignores the point at modifier - drat!
Wonder if its worthwhile asking for technical assistance from Daz?
Roygee, I think your piston could be made to work with bullet. Just mulling over your video I think the way I would do it would be to forget about constraint and pivots and actually make it properly.So have the cylinder in a tube to constrain it. Then have the connecting rod loosley attached at the piston end and at the wheel end, Then apply a ratate to the wheel and have the piston tube just keyframed still. But I reckon your rotating wheel dia would be so large the connecting rod would catch on the tube just like a real one ,so the tube would then need to rotate somewhere in the middle....... I am not sure really sure what I am talking about so ignore me......
Maybe I will have a crack at a similar thing to what you have done and see if I can learn anything.
ps .My hoops are up to about 15 ( quite high poly torus's I made with the torus plugin) ,keyframed at both end...It seems rock solid at the moment.Also I forgot to mention I am using the 8.5 beta also.
So... what are you planning to do with this rock-solid chain? Kidding.
This is very cool - thanks for the info above. I just got Curvy 3d - came with a bundle I bought. Looks really fun and interesting. I'd have never known. If I were to go out and buy one of these sculptors, I'd go for 3d Coat - just from seeing your work. Which compelled me to check out their site, and I agree. The owner is incredibly cool.
Good luck on your flying pig! I built a waterfall/moat/sandbox for kids to play in for a company called: "The Flying Pig"
Andy made me a mouse trap game on the old forum
now I know more, should relook at it
not a mechanism, more a Goldberg machine but still uses physics.
some, DT and others, did trebuchet thingies
here you go!
Age of Armour http://www.ageofarmour.com/3d/free/trebuchet.php
Beat you about the head with it ! ;-) Hee Hee.... I get it. Rock solid chains are not much use are they!
I managed to get a piston working .But Had to use a shaft constraint to keep it in the tube. If I can remember how to use dropbox I will post it ,maybe it will be usefull for Roygee. I will play about with it a bit more and load it up with more bits to see how long it takes to bring my computer to its knees.
I'd never heard of Curvy3d, I checked out the site ,the video made me dizzy with all that focus pulling........point me to the director...and hand me my rock solid chain....
Thanks Wendy I will download the scene and have a look. That was Carrara 6 which I think was before Bullet.
Right-click the file and choose: "Drop Box > Copy Share url" or something similar.
Then you just paste that url into the post ;)
By the way... Ouch! My head hurts now! :shut:
Looking forward to examining that file, Stu:)
Physics works in as much as the conrod doesn't flip in the Z-axis. The challenge is to get it constrained in an upright position. So far my efforts haven't paid off - the conrod collides with the cylinder and bounces off it, causing it to jump all over the place. Probably a matter of better mesh design and trying different densities, as well as tweaking settings.
What I'm missing in the rigid body settings is the ability to set collision distance for individual items as well as delete the animation, such as in the soft body settings.
https://dl.dropbox.com/u/7219382/Piston001.car
Right click the link and " save link as"
Here are my efforts, a bit of a mish mash really, just trying to get a feel for it. The final straw so to speak was hanging a wrecking ball on the chain. The chain fell apart, so in the scene I just moved it out of the way. If anyone can make it hold together with the ball hooked on I would be impressed!
All in all I am impressed it can do all this. This scene took about 6 or 7 minutes to run the simulation. And dont forget ,it was done in the 8.5 beta. So I am not sure it will run in a lower vers.
The next task is to try and figure out a flapping motion for some wings, up and down should be easy enough, but it would be nice to have a middle joint as well.
At least this little project is giving my brain a workout.......
Thanks for sharing, Stu:)
It runs exactly the same in 8.1. Very well done to get it this far.
I'll try reverse engineering it later - right now my wife wants me to to go shopping with her.
in my job I have to ask people what their hobbies are - the men say "beer and sex" ; the women say "shopping".
.....
thanks for sharing that car stu, will look at it when I get home
I downloaded it myself to check it was working, but for some reason the saved simulation played back all jerky and weird. But it seems ok again if I run the simulation afresh.
I hate shopping....Ive got 25 year old t shirts. Here is a test for you, Go to your wardrobe where you hang stuff and press all your hanged clothes together then measure the thickness, now do the same to the missus s. I wonder what the average ratio would be.
https://dl.dropbox.com/u/7219382/Piston002.car
I managed to keep the wrecking ball attached with a bit of fiddling, even added another one. By adjusting one of the pivots the violence of the chain being pulled was reduced and it held together. But in a way that is a compromise....what if I want to ...er.. yank my chain violenty? ( no laughing at the back please!)
It needs a magic "not fall apart button" I feel.
Anyway I've gone off at a tangent with this one,so I will leave it for now and concentrate on making an automata until I get bored with it.
But if anyone can get those two wrecking balls to clack together.......
Well, I've got my piston to work, thanks to taking a good look at Stu's model. I was correct in that the problem was a mix of mesh construction and settings. I would never in a thousand years of experimenting have gotten to those settings and it seams that you can't do a rough-and-ready to test concept and then refine - it has to be spot-on first time round:)
BTW, the roughness of the piston was caused by the conrod coming loose from the pin, then meeting up with it later on. I noticed that the hot point of the conrod was way off to one side - when I sent the hotpoint to the object and ran a new sim, it was smooth as silk.
Thanks for the help, Stu:)
choo chooo!
Good news! Interesting about the hot point,I wouldnt have thought that made a difference.I usually centre mine anyway just so I can translate and rotate withe the widget in the right place.I will have to go over that scene just to check now.
Yes there are lots of settings and they are not all in the same place,specifically the physics setting under the "scene" tab which I think maybe the most useful,thats where it lets you crank a quality up to 1000 per cent. Though I ve never understood a setting like that its non sensicle really. Its like something you say when someone asks you how you are and you say "I feel a thousand per cent".... does it make your physics 10 times better than perfect?