Animating a Cable Carrier

[Anonymous]

I'm trying to animate a cable carrier (see attached)

One end of the cable carrier chain is attached to a fixed point and the other end is attached to an object that translates in one axis only(see attached sketch) I think the sketch explains it better than I could with words.

I've tried using dynamics(hinges, gravity, collisions) but I get strange results and the scene slows down a ton.

Is there a "smart" way to set this up so that its easy to animate and doesn't require as much processing power?

I'm using Maya 7.0

Thanks a ton
-Irv

[Anonymous]

that is just a variation on the tank tread problem...search for and download Radiant Square's RS_TreadsCreation script....the basic idea is that you create a single element "tread" and instance copies of it to specific parametric locations on a cubic nurbs curve. Use a motion path to set up the parametric placement of the element on the curve and then break the animated parameter. The curve is the object that is deformed into the proper shape, taking along the instances of the "tread / cable bracket thingy" elements. But you have to pay attention to the total length of the curve, otherwise the spacing will change between the elements and it will not look right. You could use clusters or bones or what ever means to animate the cv's on the curve. Try the nonlinear bend deformer. I got it to work...here is a script editor history that I cleaned up....it has multiple moves but don't get confused by those the logic structure is there....You animate the curve by moving it on the world Z axis...

{
curve -d 1 -p 0 0 5 -p 0 0 -5 -k 0 -k 1 ;
select -r curve1 ;
rebuildCurve -ch 1 -rpo 1 -rt 0 -end 1 -kr 0 -kcp 0 -kep 1 -kt 0 -s 50 -d 3 -tol 0.0001 "curve1";
move 0 0 -5 curve1.scalePivot curve1.rotatePivot ;
move -r -0.158286 0.0670051 0.278623 curve1.scalePivot curve1.rotatePivot ;
move -r 0.0301551 -0.0251269 0.0886054 curve1.scalePivot curve1.rotatePivot ;
move -r 0.133101 -0.0418782 -0.400095 curve1.scalePivot curve1.rotatePivot ;
move -r -0.0216497 0.00837564 0.0471527 curve1.scalePivot curve1.rotatePivot ;
select -r curve1 ;
nonLinear -type bend  -lowBound -1 -highBound 1 -curvature 0;
scale -r 1 0.301535 1 ;
setAttr "bend1Handle.rotateX" 90;
setAttr "bend1.curvature" -0.2976;
setAttr "bend1.envelope" 1;
setAttr "bend1.curvature" -1.4214;
select -r curve1 ;
move -r 0 0 0.377813 ;
select -r bend1Handle ;
setAttr "bend1.lowBound" -1.2396;
setAttr "bend1.envelope" 1;
setAttr "bend1.highBound" 3.6364;
setAttr "bend1.lowBound" -3.0578;
setAttr "bend1.curvature" -2.2148;
setAttr "bend1.lowBound" -2.2314;
setAttr "bend1.highBound" 2.1488;
setAttr "bend1.curvature" -0.6942;
setAttr "bend1.lowBound" -3.0578;
scale -r 0.288047 1 1 ;
scale -r 1 0.455188 1 ;
setAttr "bend1.lowBound" -2.2314;
move -r 0 1.08698 0 ;
move -r 0 0 0.149441 ;
move -r 0.705012 0 0 ;
move -r 0 0 0.86094 ;
move -r -0.260005 0 0 ;
select -r curve1 ;
move -r 0.0553952 0 0 ;
move -r 0 0 -1.157303 ;
move -r 0 0 2.180142 ;
move -r 0 0 -0.418271 ;
}

[Anonymous]

here is my 2008 ma....nothing new to cause problems with unsupported features. I am actually suprised it was so easy..one has just the curve and the other has cubes instanced via a motion path to the curve.

104_iIpCevbDpLpzzYwCzlnR.zip

[Anonymous]

Paulalso,
Thank you so much for your help. That is definately the "Smart" way. It makes perfect sense, and I am trying to redo it on my own. I wasn't able to open the files, but I used the script and it works great. I'll post back with progress.
Thanks again
-Irv

[Anonymous]

Okay... After some tweaking and parenting, I've got it animating very nicely. The only part that I couldn't really figure out was how to attach multiple instances of the "link geometry" to the motion path. I have to attach them one by one and that creates new motion path nodes every time. Its not a huge deal because there aren't that many pieces, but it still seems like there should be a better way.
Thanks for any help
-Irv

[Anonymous]

I attached a really quick clip of the cable carrier in action. I wish I could show the rest of the animation but it has some sensitive stuff in it. Thanks again Paulalso.
-Irv

710_6H93imvVYAXk1ACkrkDt.mpg