Inflatable structure with Kangaroo

I`d like to create a inflatable structure with Kangaroo, which is “trapped” inside a cage and is pushing through the open spaces.

As a collision object (the cage) I used a box and Multipipe to get a volume out of the wireframe. Inside the cage are 8 different mesh spheres, which should inflate and also collide with each other.

The collision between the spheres is working good but the spheres are pushing through the cage at a certain point.
And I dont know what Im doing wrong.

Kangaroo (15.1 KB)

Hi @kevin.huegle18 , have a look at the definition I posted in this thread


For a better collision with the Multipipe object, divide the curve segments…

I would use TriRemesh on your mesh spheres. It leads to a nicer result.

And I don’t see a benefit of using the bouncy solver.

Kangaroo (30.7 KB)


@martinsiegrist @DanielPiker

Thank you !! This helped a lot

If I increase the target volume before starting the simulation, the same problem reappears at some point. If I change them during the simulation, it works much better.
So start the simulation with a low target value and than increase it slowly.

Is there a parameter I could change to avoid this?

You have the right approach increasing the target volume slowly.
If there is a big instantaneous difference at the start between the initial volume and target volume, it can cause parts to move so fast in one iteration that it misses a collision.

Another alternative might be to combine this with the the edge collision goal I shared here

It would probably be slower than just checking the vertices for collision with the frame, but less prone to passing through it.