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My rigged character woobles and shakes with no reason, I checked the keyframes on the feet and body and they are not keyframed so I don't know what is causing this.

enter image description here

I tried deleting the keyframes of the armature but still doesn't work, the shaking problem is still there.

enter image description here

It seems changing the value on W Rotation in Quaternions makes the shaking movement

enter image description here

https://drive.google.com/file/d/180VdsMHlKyVVHsp2ex8kLoor7VqCUYJD/view?usp=sharing

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    $\begingroup$ Could you please describe more precisely the issue, provide screenshots or GIFs, and even your project file using blend-exchange.com so that we can better see for ourselves and find a solution? $\endgroup$
    – Lauloque
    Commented Jul 4, 2022 at 6:50
  • $\begingroup$ I added a GIf for better understanding of my problem, I forgot about that sorry $\endgroup$ Commented Jul 4, 2022 at 7:18
  • $\begingroup$ are you sure you don't have a degree/radians problem? $\endgroup$
    – Chris
    Commented Jul 4, 2022 at 7:52
  • $\begingroup$ How can I check that buddy? $\endgroup$ Commented Jul 4, 2022 at 8:09
  • $\begingroup$ I couldn't upload my blend file to blend exchange because I get an error saying my blend file is not a file supported. Can I paste a google drive URL? $\endgroup$ Commented Jul 4, 2022 at 8:12

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The issue comes from the way you setup your IK chains, I.E. the one that goes from your head all the way down to your hip bone.

IK is quite a sensitive thing. The longer the chain with no clear direction, the more it can give erratic results.
That's why most of the time, IK chains are about two bones long, and with a separate Start and End point that are isolated by the IK chain's influence. Because if you ask a bone to be both the effector and the affected, both roles will compete with each other. Like an arm IK only affects what's between the shoulder and hand: arm and forearm. Or a leg IK is only between the hip and the foot: thigh and tibia.

Your current setup does not have an isolated end point, and the Start point - although isolated - isn't the right one: you currently have no way to freely orient the head as it is part of the chain.
It starts from the Bone.027 and just influences all the chain down to Bone that acts like the hip bone. This can only cause issues.

First, let's prepare the rig to make it easy to use and will overall produce better results.

Preparing the rig

1. Renaming

I started by renaming all the bones so that we don't get confused and know what is what.

To make this process faster, delete the leg and arm bones on one side, so that you only have one half to take care of. Make sure to put either .r or .l at the end of the arm/leg bone names to mark their side. Then select that half and go to the menu ArmatureSymmetrize to make a mirrored copy of the arms/legs with the correct side naming.

2. Clearing transforms

In Object mode, select the armature and hit ⎈ CtrlAApply Location and then again for Apply Scale.
This is to fix your armature's origin not being at the world center, and the scale being not equal to 1. You should also do this with your mesh objects to avoid deformation issues.

3. Fixing the rig structure

Looking at the model, some bones were at the wrong place, some were not needed at all, some other bones were missing, ... So I went ahead and changed that.

The bottom line is, look at your model, think where a deformation should happen and put a bone there.

And no matter how you build your rig, you need a "root" bone, that is at the top level of the bones hierarchy, and will serve as your rig's base placement, and also is where you will put any mesh influence that isn't taken care of by any other bone.
This bone is not just useful, it is sometimes mandatory in some softwares, so it's a good habit to always have one to avoid surprises when exporting your rig elsewhere.

And I finally removed the IK constraints and animation, so that now we can correctly rebuild a proper IK chain.

The final result should look something like this:

reshaped the rig

Making an IK chain for the neck

I'm using the neck as an example, but this would be basically the same on any chain.

1. Preparing the bones

First, we will need a "target" bone for the chain. It's the bone that the IK chain will "start from", the starting point. It's safer to not use a bone that is already used for deforming, so let's make a new one:

In edit mode, select the dot between Head and Neck.002, and hit EZ to extrude a new bone upwards. This will be our neck's IK target bone, so let's name it Neck_IK_Target.

We need this bone to follow the Head bone, so let's parent it to the Head bone with "connected" option off.
We also need the Head bone not to follow the neck bones (as they will be influenced by the IK, which the head will be the influencer), so let's parent Head to Torso with "connected" off too.

Now depending on your needs, Neck_IK_Target should either be independent of the body movement or follow the torso, or maybe even both depending on the animation.
I will not cover how to make a setup that allows to do both, so let's just pretend we need it to follow the torso: Select Neck_IK_Target then ⇧ Shift select Torso and hit ⎈ CtrlPMake Parent Keep Offset.

We will probably need to make sure the curve of the neck points the right way and animate it, which is usually done by having a "pole target" bone the IK chain points towards.
Select Neck_IK_Target, duplicate it with ⇧ ShiftD and move it somewhat above and midway the neck. Let's name it Neck_IK_Pole. The result:

neck IK preparation

2. Setting up the constraint

Back in Pose mode, select Neck_IK_Target then shift select Neck.002 and hit ⎈ Ctrl⇧ ShiftCInverse Kinematics. This will add an IK constrain to Neck.002 with Neck_IK_Target set as target.
We need the chain to influence only Neck.002 and Neck.001, so set the Chain Length to 2.
Finally, set the Pole Target to Neck_IK_Pole, then the Pole Angle to 90 (the pole angle needed depends the orientation of the bones, so can be different from one setup to another. Just use whatever seems to make the chain point to the right direction.

The constraint settings should look like this:

IK constraint settings

Now you should have this result:

demo IK chain

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  • $\begingroup$ That's an awesome work!! Any chance in sharing the blend file? I'll take a look at it thanks very much $\endgroup$ Commented Jul 4, 2022 at 14:25
  • $\begingroup$ What a patient :) Great work. Would be good to mention Bone Properties > Relations > Parent $\endgroup$
    – vklidu
    Commented Jul 4, 2022 at 15:04
  • $\begingroup$ I rigged it properly following your instructions! thanks a lot buddy $\endgroup$ Commented Jul 5, 2022 at 5:54
  • $\begingroup$ @AlexisRivera Glad it helped! Though sorry, I didn't keep the file :o $\endgroup$
    – Lauloque
    Commented Jul 5, 2022 at 7:36
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    $\begingroup$ @vklidu Thanks! I thought about mentioning this and other things, but the post was already getting long and detailed so i had to cut some things out x) $\endgroup$
    – Lauloque
    Commented Jul 5, 2022 at 7:38

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