7 replies to this topic

[mantragora]

So I'm sitting third day on this, trying to figure out how to simulate it.

Basically, cables should be pinned on one end to some moving body and on second to this plug that splits them. Simulation should be mutual. If anything hits cable (any cable, lower or upper), plug comes with it, something hits plug, cables comes with it and of course cables and plug can collide too (in places where they are not pinned). I've been looking at help examples but can't find anything similar that I can use.

I was thinking that maybe I could use RBDSpringConstraint for plug and pin cable to it, but then I don't quite get how to affect it's movement when something hits cable. Even than cable movement is also strange because it's pinned to this plug and follows it when it gets hit by something, while in this moment plug should follow cable rather.

I would be grateful if some DOP master could share his knowledge and help a little.

Attached Files

•  sim_template.hip   111.98K   19 downloads
•  temp.jpg   34.28K   34 downloads

Edited by mantragora, 10 June 2012 - 10:22 AM.

[mantragora]

Just found out about ApplyRelationshipDOP. It can create mutual relationship but from what I read is hard to setup. Any tips ? Come on, don't be shy !

[mantragora]

I got something like this. It looks that it works but it jiggles as hell. Maybe I should just modyfy geometry, make plug hollow inside than just pin cables ends together and leave this Plug not pinned, just brute force simulate like in real world if it had cables inside ?

Heh. Funny thing. I got full rig setup ready with dynamics. Long cables that goes thru whole model and inside it, moving with legs. Head cables. And I left *THIS* part on the end because I was thinking that it will be the easiest part. Now rig is ready last three days, and I still can't solve this .

Attached Files

•  wire_test.hip   406.94K   38 downloads

Edited by mantragora, 11 June 2012 - 01:08 AM.

[Marc]

I've never used the apply relationship DOP, but I do know that there's a big thread about it on the SESI forums. I think Macha was trying to do some crazy stiff with a chandelier.

Not much help sorry, but hopefully it points you in the right direction.

M

[mantragora]

Yeah, I've been digging this topic and two others. There is a nice example in help that shows some nice mutual interaction but still all those expressions used there need some time. I'm trying to bend my mind around it but I think I will leave AplyReationship for feature tests. Now I will go with this brute force method which, hopefully, should work.

[mantragora]

So it didn't work out.

I made plug hollow inside. Collision geometry is generated correctly. Cables pinned together reacts nicely, but if I add this RBD plug into mix, everything theoreticaly reacts as it should. There is one problem. Cable can't stop streching under plug mass. Even if I make plug very light, it still streches cable forever.

Help.

PS> you need to turn on Plug Template RBD object to get plug into sim. In the attached file I forgot to leave in turned on.


EDIT:
There is another thing I missed before. All those constraints have "Mirror Constraint" option that makes all object specified in this constraint mutual affectors. But this doesn't help me since I can't get nice movement if I pin plug to cable and cable to plug.

EDIT2:
Another idea is to make RBDSpringContraints that replaces cables (each line segment in cable will be = one RbdSpringConstraint) and are pinned and follows cable simulation. Than I could just pin last SpringConstraint to plug and it would not strech cable. But this is only idea, don't know yet how to make it.

EDIT3:
Just checked this "Mirror Constraint" option. I DON'T like it. Simple scanario, one cable and pinned object on its lower end. Instead of going down with gravity, pinned object started to fly horizontaly taking cable with it. Just like there was no gravity at all.

Attached Files

•  share.hip   609.48K   27 downloads

Edited by mantragora, 12 June 2012 - 10:04 AM.

[mantragora]

Is there possibility to get position information from inside os SopSolverDOP back into DOPS? I would like to get info of each line point and drive something in DOPS with it. I tried with "origin()" expression but it retuns "0" always.

[mantragora]

Heh, just found this on Sam blog.