Rear Legs twist when character is moved.

We are using Modular Rig to build out quadrupeds however there is an issue with the hind legs whenever we try to move the character. Even though the Pole Vector controls remain consistent, there is an unwanted twisting in the upper thigh that rotates inward when the global controls are moved forward and outward when the global controls are moved away.

This unwanted behavior appears to be happening in the hamhock_l_01_rig and hamhock_r_01_rig joints that rotate when the global control moves but also when the IK foot control is raised. This appears to be a known issue but I cannot seem to find a fix.

Any ideas how to remedy this because it is severely hindering our animators.

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Steps to Reproduce
We are currently using Unreal Engine version 5.8.1

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Hey there,

Do you have repro steps for vanilla Unreal or a project that you can send along with a skeleton that it happens on? One of the issues with modular rigs is that the skeleton that you apply them to really matters.

Dustin

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Hmmm so the current skeletal mesh is under a pretty strict NDA so I can’t share that. I can try to see if I can find a generic quadruped and do a quick skin pass and share that skeletal mesh.

If you’re able to check out just a generic FBX, I could share that as well. I did make sure the orientation looked good but there is a bone connecting the rear leg chain to the pelvis (I included an image to show that bone). Not sure if this might be causing a problem as well.

Let me know if you’re able to look at any of these things. [Image Removed]

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A generic fbx with no mesh is just fine, it’s about the bones and evaluation of the rig on them.

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Oh sweet! This is the quadruped skeleton that we’re currently using. Thank you again for taking a look!

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Thanks!

I wasn’t able to repro, but I think this might be related to what you bones you might be using. Here’s the setup that I had:

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This worked well and didn’t cause any jitter or weird bone movement.

Dustin

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YES! This fixed the issue as well as fully clarified how sockets work now! Thank you so much!

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