Why is my Ragdoll behaving oddly?

Hello, I’m having some problems with creating ragdolls on my skeletal meshes. Here I have a skeletal mesh as you can see here. I think it looks pretty normal, however when I go into the asset browser and right click > create > physics asset, the first time I simulate it behaves unexpectedly, kind of floating around upside down in a weird way like this. The second time I simulate it completely freaks out with limbs all over the screen.

I figured maybe the way the collision was being generated on the skeleton was overlapping poorly or something so I tested by deleting all of the collision bounds and creating just one at the hips. It performed as expected with the whole mesh just dropping to the ground and rolling around. After adding one more up on the next chain of the spine however, this happened. Adding another up the next chain of the spine simply made the stretching worse and caused it to shake around more.

I imported this mesh from blender but the animations all work as expected etc. I have another model that I created in blender with a completely different skeleton and the same thing is happening there. Any ideas on what could be causing this? Thank you!

Hi greynz,

Have you looked through our PhAT video tutorials? If you haven’t, perhaps they might have something that could help troubleshoot your issue.

Oh, this kind of thing was happening to me too, I think it’s a bug.
I’ve been trying to get a ragdoll working for my mesh for a while now, and was close to posting a question of my own.

It seems to simulate OK for a single bone, but then after adding another it extends the second bone and locks it a certain distance from where it should be, even when set to not collide with the first - very weird. I’ve also watched all the Phat videos but everything works as expected in those without this problem of course.

If you’re still having this issue, feel free to post your .fbx and we can troubleshoot it. If you’re not comfortable posting it here then you can Private Message me on the forums with a link to the file on Dropbox, etc.

Thank you, i’ll send you the link :slight_smile:

Hi greynz,

Whenever you have time, I sent you a PM of the forums a few days ago with questions about the fbx file.

If you two find a solution, please be as kind as to post it here as I have the same issue. Thanks.

This is probably an issue with your physics bodies. The default physics asset that is generated is purely a starting point and will not work for nice ragdolls. You should check out the tutorials linked above to properly set up your asset.

These problems are usually caused by overlapping physics bodies. When simulation starts they will instantly try to separate from one another causing terrible things. Also you will need to limit specific joints to make them behave the way you want.

Well I figured it out, the problem was with my skeleton. I forgot to tick the box that causes it to export with deformation bones only, so my skeleton had a bunch of extra things floating around (elbow trackers, knee trackers, hands, feet, etc.). After I got rid of that stuff it successfully worked the way it should.