Cart with RigidBody2D

[jeffreywalther]

Hi,

I’m having a problem with PinJoints and RigidBody2D.

I have a cart and two wheels, all of which are RigidBody2D objects. Each wheel is pinned to the cart.

The cart rolls down the hill automatically. So far, so good.

Problem:
One of the wheels moves back and forth under the cart, depending on how fast the whole cart is rolling down. I have Softness set to 0 and Bias to 0.9 for both wheels. Nevertheless, the joint seems to “stretch”, or at least the wheels aren’t absolutely fixed to the cart.

Is there a way to fix the wheels absolutely to the cart so that they only rotate?

Jeff

[gertkeno]

I’m pretty sure having rigid bodies as children of other rigid bodies is going to act up, the parent’s transform will affect the childs in a non-physical way which is against how rigid bodies should only move by physics.

[jeffreywalther]

@gertkeno
Thanks! Yeah, you were right.

I had to create my RigidBodies under a parent node. My mistake was placing the two wheels under the cart. Thanks again!

Working node hierarchy: