Mechanical Rigging - Linking Bones To Channels.

[ofer]

Hello! Im in the process of rigging a robot model I created. The robot is quite simple, and it consists of several parts and bearings connecting them. The bearing is something like a tube, with two sliders on it. I created a digital asset where I have a parameter for each slider's position (amount of rotation) on the tube. I want these parameters to be set by the degree between two bones. My problem is that when creating a chain with IK, moving the goal doesn't change any visible channels.

My question is, what channel can I use, or is there a better way to achive what I want?

Basically, what im looking for is a way to use bones with IK without capturing geometry.

[michael]

you can get the bone rotations from your IK solver

check out the chop() expression

[ofer]

OK, Ill check it out. But is it the right way to rig a mechanical setup?

[ofer]

Hi! I was wrong, and the bones rotations are set as expected, so I can simply do a ch("../../bone/rx") and works. Really cool. It seems like the right way to go. I do have a little problem though.

I have two bones going through my bearing, each controls one slider. But I need the whole bearing to move with the bones. So what I did, was to add a transform SOP with the pivot manualy positioned at the chain's root, and then used bone1's rotations. It works well, but I don't like to manually set the pivot point. I couldn't find how to get the root's null object position with expressions.

Any ideas?

[edward]

It's hard to say what you're doing wrong unless you have an example hip file.

Anyhow, you can always get the world position of any object using vtorigin("/obj/someobj", ""). To get the componenets, use [] notation like this:

vtorigin("/obj/someobj", "")[0]

vtorigin("/obj/someobj", "")[1]

vtorigin("/obj/someobj", "")[2]

[ofer]

OK thanks, I can also use the bounding box of the first bone. Ill try both methods.