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Physics Asset: How to prevent 'bending'?


I'm trying to make a physics asset for a robot, with multiple pieces working together, but I can't stop the pieces from 'bending' or 'stretching' out of place, like in the picture: alt text

  • the skeleton tree starts with the 'foot' of the robot, in Kinematic mode, with each arm 'nested' into the nest until you reach the top (8 pieces in total).

  • each arm has a physics constraint both backward (up the hierarchy) and downward (down the hierarchy)

  • so far I got best results with the weights going down 10x from each arm to the next (so 10k for the base, 1k for the first arm, 100 for the second arm, etc), like so: alt text

Basically, I want the constraints to apply without any bending, without any flexibility. I've tried - linear/angular damping of the bodies - adjusting the Swing Motion constraints (soft constraint with 50k stiffness or hard constraint, or free constraint) - adjusting linear limits with 50k stiffness, or had constraint - adjusting constraint behavior (small or larger projection linear / angular tolerance..) - changing the weight, switching on/off gravity on the different arms ..and of course variations and combinations of the above.. I've been playing with this for a day now, and when I solve one joint, the next joint give me problems. When I solve the next joint, the previous one starts bending again.. it's like a game of whack-a-mole.

So, I'm asking for help here..: What can I do to get the constraints to just apply!?

Product Version: UE 4.21
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asked Feb 15 '19 at 12:09 PM in Using UE4

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Warner V
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Alright, finally I found two things that were happening here:

  • Importing the Skeleton Mesh from Blender, the scaling if off (unless you follow description in **link**)

  • From one bone to the next, things work better if you reduce the weight by an order of magnitude (10k, 1k, 100, 10kg etc.)

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answered Feb 19 '19 at 11:11 AM

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Warner V
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