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Physical animation casues skeletal mesh to rotate to wierd angles

So i am trying to make a physics based melee game. I've ran into a problem with the physical animation. It appears that it is trying to rotate the mesh to a specific angle around one axis. This angle chages depending of the rotation of the mesh on another axis. Im posing videos of the problem below, ive turned the gravity off for easier demonstration. (Sorry for the unnecessary soundtracks, diddn't know i recorded audio)


On this next one ive turned off physical animation, you can now see the UE guy dance freely to his target rotation.


Do anyone know what causes this? and how to fix it? Any help would be appreciated.

Product Version: UE 4.19
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asked Sep 19 '18 at 11:23 AM in Blueprint Scripting

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I think I found the reason for it. You should not apply Physical Animation to pelvis (or any bone that has no physical body as a parent). This makes Physical Animation try to reach the target orientation for pelvis in world-space rather than in local-space (relative to parent). I guess that's because the parent is the world in that case.

I simply zeroed strength for pelvis bone in the Physical Animation Profile and it works fine now.

Edit: Well, it works for some cases - where orientation strength is low. Seems that Physical-Anim-Component is not fit for applying larger forces as it adds energy to the system which then becomes unstable (weird twisting etc). It's because normally active ragdoll would use joints/motors between existing ragdoll bodies to reach target local rotation. There would be no problem then. I looked into the code and Physical-Anim-Component uses joints to non-existing kinematic actors (clones of our limbs) to achieve movement/rotation of ragdoll limbs. Those kinematic actors are moved where animation directs them and they "drag" real physical bodies with them. This is very non-physical in terms of how real world works and can result in very unstable simulation. It's like there is a magical force that moves your body around and not your muscles doing it.

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answered May 02 '19 at 11:06 AM

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