How can I make this IK better / fix this

I’m trying to animate this rig procedurally but it seems very stubby/choppy. how can I improve this? also, I’m using the Roblox IK Control for the legs; for some reason, the legs only bend when the target is above the mid limb. I’m trying to make its legs bend (Second Video)

I’m not sure if I’d be of help but some information that could be useful in diagnosing the problem…

  • Can we see a picture showing the skeleton of the rig?
  • Are you using any form of constraints? If so, those have a big effect in limiting the range of motion, so be careful with those, perhaps give them a higher bending range
  • More articulated parts make it easier to reach the target, consider this in the design of the rig.
  • Since this is a bit vague from the videos, how many targets are you using? Is it one per leg, or one every two legs? Are they in the center of the rig or are they accurately placed for each foot?
  • LookAt or Transform/Position?

That’s all I can think of for now off the top of my head.


This is the rig. I think it might be that the foot bone is halfway to the bottom

Im using Position, Transform makes the grounded legs move even while the target isn’t moving. one target per leg

Is the third joint supposed to rotate, or is it supposed to stay in the same rotation as its parent?
image

If it is supposed to stay in the same direction, I do recommend to keep the rig with this amount of joints, and move the third joint down to the tip of the leg, where it makes contact with the ground.

If it is supposed to bend, then you will have to add another joint down at the bottom that is connected to the third joint.

The IK is trying to make the joint of your choice to be on the position of the target, so basically, as it is now, it won’t start bending because the target is waaay below the joint that is meant to be on the target position. The engine will interpret this as “Oh, I need to keep the limb straightened to get the maximum possible reach, because it is so far”

[EDIT] I made a quick MSPaint diagram of what the IK is trying to do, to give a graphical example:
image

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The image helps alot. The top joint acts as a shoulder and I think it might make it better if I edit the rig and move the foot to the base of the foot.

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Glad it helped! And for sure. IKs care little to nothing about the part you can see in the mesh, only the joints in the rig matter when setting them up.

As it is right now, the IK controller thinks the mesh has super short legs, as if the robot was a dachshund dog. Hope this also helps to anyone else having this kind of issue, because I’ve seen more people struggling with this same problem.

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