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I have some connected rigid body objects (a ragdoll). When I let physics do its thing, the ragdoll doesn't just fall - it acts as if some mysterious force hits it.

While investigating what might be the cause for it, I realized there's something (mysterious force) that affects the ragdoll. It's positioned roughly where the ragdoll is. To demonstrage this, if I duplicate the ragdoll and move the duplicate 2m to the side, the duplicate doesn't hit that mysterious force.

Here's how it looks (first 10 frames, slowed down): enter image description here

For completeness, I also tried just moving everything around, and indeed there seems to be something roughly 2.5 meters above the origin:

YouTube video: Blender 2.9 mystery force affecting ragdoll falling down

Before I rewatch Stranger Things and look for clues there, any suggestion on how to find what's causing this strange behavior? How to identify that invisible force?

FTR, Here's the .blend file in question.

Thanks.

Note: this is a followup to a previous question I asked - at that point, I thought the problem was with the constraints between the objects.

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The mysterious invisible force is 12 copies of your ragdoll. They are not in your scene but in your blend file. It looks like these lost objects are still used for collision detection.

To get rid of the copies, select Blender File as Display Mode for the outliner. Look for Objects and expand it. If you select everything in the viewport, then you can easily see in the outliner which objects are used in the viewport. Delete the other unwanted copies. lost copies

If you want to see the hidden copies, create a new file, delete everything and use File → Append ... to append the collections RigidBodyContraints and RigidBodyWorld from this file. These collections are used internally by Blender and are connected to the lost objects. This way you can append them easily to your scene.

13 ragdollsRevealing the 12 hidden ragdolls

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  • $\begingroup$ Amazing! I wrote a script to create the ragdoll, and ran it multiple times, but deleted all existing ragdoll objects in the beginning of the script. Can you think of a reason why they weren't "fully deleted"? Thanks. $\endgroup$ – Barak Mar 27 at 12:49

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