mechanical shoulder rigging
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I'm trying to figure out how to rig the shoulder of this character so that it moves in a mechanical fashion instead of completely together (as a shoulder normally would). This character is a robot, so it would make sense for the different parts of the shoulder to serve different rotation purposes.
More specifically- I'm wanting the selected piece of the model (in the image) to rotate according to the shoulder but have its positioned constrained to the collar. I'd also like the cylindrical piece (inside the highlighted object) to rotate freely but have it's position constrained to stay in place. That way when the arm is rotated up (think T-pose) the cylinder rotates as well but the highlighted object stays in place.
I currently have the entire mechanism weight painted to the shoulder joint and am trying to understand what needs to be done to make this work as I'm intending? Do I need to remove the weight painting from the mechanism and use constraint tags on those objects in particular?
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Hi rent-crash,
Mechanical rigging can be done with just the objects while setting their Axis to the "rotation point". After setting up, use Freeze Coordinates to reset the parts quickly (Reset PSR).
Any rotation is best set up when the rotation axis aligns with the Joints, if you use that rig. In you image, there is nothing aligned, which will cause problems.
It can also be done with Weighting since Joints and Weights are "just" specialized Deformers.
To get deep into all of that, please have a look here:
https://www.youtube.com/live/5dNmL-NpU_w
https://www.youtube.com/live/4sOTW4xYQvk
https://www.youtube.com/live/jGCRKX5Zz5MIf I understand the cylinder-idea correctly, I am not clear how the shoulder would move, so either a constraint (use the offset options to adjust orientation) or a new joint would be needed.
Mechanical rigs can often be set up by just positioning the joints carefully and making the objects of the character a child of the joint that should drive it.
All the best
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Hi Dr. Sassi,
Thank you for the further information. I will check out the resources you provided.
Will likely try and go the constraint route as that seems more straightforward than adding more bones and re-weight painting things. Appreciate your feedback
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Hi rent-crash,
I would place the part of the arm gimbal/cardan connector under a Null rig and connect the null with the clavicle joint. This might help avoid the problem of rotating things around an object that is not aligned.
My typical suggestion is to do that in an empty scene, in this case with two joints only, and connect some Stand-in objects to focus only on the setup.
All the best
