Robot arm+wires?

Ok, so making a robot arm, is easy. simple rigging (in my opinion). however, how does one get wires to dangle off the robot arm and kind of sag, but pull after the arm when it moves, and at the same time not strech like real wires?

Example:

http://www.botmag.com/issue2/images/bottom2.jpg

The wire is strung in between two arms and will become taught if the arm is extended all the way, and sag if it’s bent. how would I achieve this? softbody wouldn’t give the rigity of a real wire, and so that dosn’t really work :confused:

I’m guessing shape keys or bones, but I’ve never tried something like that.

softbody wouldn’t give the rigity of a real wire, and so that dosn’t really work :confused:

does doing something with the “stiff” settings not work for you?
i read one article that armatures could also work for that purpose, but needs also work if the softbody did not do the job.

hmmm :confused: I was kinda hoping I’d somehow be able to make a armature or something track to the ends of an arm rig or something like this:

It´s just an idea, but i think it could work like that:
At the final Mesh take two vertices that are in the place, where the rope should be hanging and add hooks. Take the wire and make it a softbody. Create a Goal-weight (map) of 1 at it´s ends. Attach hooks there. make the two hooks of the wire children of the two hooks on your machine. I didn´t try, so i don´t know whether that really works… And it will only work if hooks are moved with a deformed mesh… i don´t think so, but i don´t know :slight_smile:

Edit: Oh my… i just realized the nonsense of my post…so…just ignore it

You can get a visual approximation by :

  1. using an armature consisting of 2 bones and 2 hooks that are parented to individual bones (at the tip on one bone and at the root of the other - then you go into Pose Mode and select the empty/hook then the bone you want to parent it to and Ctrl-P)

  2. then you add a curve, make it 3D, align it so that its end and start points match where the empties are (use the Shift -S hotkeys to snap your cursor etc. and it also helps if you convert the curves to a NURBS type because with beziers the entire handle is selected but with NURBS you can select just the center)

  3. then tab into Object/Pose Mode and select one empty, then shift-select the curve, tab into Edit Mode for the curve, select one of the endpoints and Ctrl-H -> Add, to Selected Object (the hook you selected before going into Edit Mode for the curve) … Now just do that to the other hook and endpoint for the curve .

Now when you move/ rotate the armature joint the curve will be “attached” to the endpoints of the armature bones via the hooks and will behave in Object/Pose Mode like a bezier or NURBS curve would in Edit Mode … You can even "lengthen/shorten"the curves just by rotating the empties only … Now this is only an approximation, the wire/curve length won’t always be constant … but visually good enough for most applications …

Now if you use the hooked curve along side the array modifier you can easily generate a simulation of the robotic wires in your picture into an animated mesh object easily …

Check this web site out. http://www.blender.org/documentation/htmlI/x7891.html
It shows a hydraulic setup with hoses, but it will work good for your application.
Using parented armatures with an IK solver modifier you make the whole thing automatic. As you move your main rig around the wires will follow.

Good luck