Simulation of delivery (Childbirth ?)

Support Animation and Rigging
1

Hello everybody !

(First, sorry for my english !)

I need your help ! Pleaaaaase ! :’(

I want to do a simulation of delivery ( Childbirth ?) for a research.

I have two objects for this: the pelvis in the body of the woman and the head of the baby.

And I have a specific path (trajectory ?) for that.

On the head of the baby, I put (?) a softbody and a collision.
And on the pelvis I put a collision.

result :
The head of the baby follows the path in the pelvis , and when it touches the pelvis, the mesh becomes soft … It’s good for the moment.

the problem is it too soft , I want that the head is little more rigid , and That When The head touches the pelvis , it is Pushed back.

Sorry again for my english !

I tried to mix a soft body and a rigid body, but It doesn’t work ! (or I think that I don’t know how mix the both ! -_-’)

I tried with a physic “Cloth”…
I tried with the constraint “Hook”…
I tried a lot of things !!!

I want just that the head follows the path in the pelvis, and when it touches the pelvis, it deforms and it’s pushed back.

it’s like a ball and a cylindre, the ball goes in the cylindre and it’s pushed back when it touches the “walls” of the cylindre.

While here, it’s just like a cloth or a thing more rigid, who when it touches the pelvis, it slides along the bones of the pelvis.

Do you have a suggestion ?

Or any help ?

If you want a video to better understand, don’t hesitate to ask me !

Pleaseeeeee ! :’(

Pity !!! :((

Thank you in advance !

2

Moved from “General Forums > Blender and CG Discussions” to “Support > Animation and Rigging”

This could also go in the Particles and Physics Simulations subforum, but really, this isn’t something I think you’ll want to rely on physics simulation for. You’ll have a lot less headache and pain if you actually rig and animate it.

3

I agree with Fweeb - You have the head on a trajectory, presumably using a Follow Path constraint yes?

So far so good. From what I know about child birth in Humans, No, I have never actually had a baby… The pelvis is forced open, with the two pubis bones separating, the pubes (plural of pubis) bones in women are not fused as they are in men at the Pubic Symphysis. The pubis bone is connected to the Ischium and this to the Ilium bones on each side. So the hinge point is where the Ilia (plural of Ilium) meet the sacrum at the base of the spine. There may also be some flexing between the Ischia and pubes bones.

So, what I would do is to create an armature with a bone running from the joint of sacrum to Ilium then another connected bone to the joint of Ilium to pubis, then another connected bone for the pubis on each side. Assign the skeletal mesh to these bones and then animate an opening action of the pelvis as the head passes through. You might like to use a driver or Transform constraint for the Ischia and Pubes bones, so they rotate a proportion of the rotation of the Ilia. Are you still with me on this? That way when you rotate the Ilia to open the pelvis, the Ischia and pubes also open a little. Make the opening animation sufficient to squeeze the head through (Ouch!) then close them once the baby is delivered.

More anatomically astute BA members, or indeed those who have had babies themselves, might like to comment on the timings of such an animation, but I believe this is not a super-fast process, say like a pop-gun being fired and may well include several distinct movements, accompanied by several ear piercing shrieks and many swear words… :eek:

Cheers, Clock.

Here endeth the anatomy & Latin lessons…

4

And biting! Don’t forget the biting…I’m not the only one who has been bitten by the mother, right? RIGHT!!!

5

The best way is almost certainly to rig everything and tweak the animation by hand. However, if you really need it to be a simulation…
I know exactly what you mean about the softbody mesh being “too soft.” This is because there is no internal structure to it so it collapses very easily. I would suggest checking out the Molecular addon which uses particles to generate a solid mass with springs between each particle. This lets you create a volume which can be bouncy or stiff as needed for your simulation. In theory, you could create a second particle system for the pelvis with different stiffness settings. You might even be able to model the hard bones and have them interact with the surrounding soft tissue, but setting that all up correctly is going to get very complex. In the end it will be easier to rig the mesh and “fake” the interaction.

6

You are sooooooooo right, but I was slapped/punched - ouch. Apparently the pain was all my fault for something I had done 9 months earlier - there ought to be a “statute of limitation” on such unwarranted acts of reprisal.

Cheers, Clock.

EDIT:

On a less jovial note, isn’t the baby’s head slightly squashed by the delivery process, given that the skull bones have not yet closed at the time of delivery?

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I don’t think blender is capable of delivering a scentifically acurate simulation of child birth. So it’s a bit pointless to do your animation with rigid body or soft bodies. It’s better to do it by hand as Fweeb suggest…

8

I agree with this - so do most women, who seem to think that “Faking It” is a good idea…

Cheers, Clock.

PS. Sorry to @anaisg - we seem to be taking this not too seriously at times, and Welcome to BA of course.