Configurable joint, different anchors per axis?

Unity Engine
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1

I don’t really know the best way to explain this, but I want to have each axis of rotation work around a different pivot.

For example, lets say I have a rigidbody body that has its z rotation limited to 30⁰ and the anchor is 2 units to its right. I want to be able to rotate around the y axis relative to the rigidbodys own position rather than the anchor, such that the z rotation causes it swing up and down around the point 2 units to the right, but the y rotstion simply rotates it around its own up axis.

2

Sounds like two joints to me.

[ A + joint(B) ] [ B + joint(C) ] [ C ]

Do you have a real-world example of an object that behaves the way you describe? Or can you explain what your objects are, to make it more obvious what you’re trying to achieve?

3

Car suspension. I want the wheel to be able to steer, but when i rotate it about the y axis, it pivots around the point its attached to the vehicle, instead if its own up axis.

I would prefer to just have the wheel rigidbody attached directly to the vehicle, rather than require multiple rigidbodies connected in series.

4

That’s definitely two joints. Or use the Wheel Collider for its positioning capabilities, which keeps the whole car under one rigidbody. You can do the tire math yourself.

5

I already have a better solution than the wheel collider so there wouldn’t be any point in using that.

If it requires more than 1 joint then i suppose i will have to use 2 or find a work around. Thanks.

The reason i want to use joints is because i want to have suspension that can move in any way i like, rather than just straight up and down.

6

I’m using a hierarchy of ArticulationBody joints for this, my revolute steering joint is a child of my prismatic suspension spring, it’s working well for me. My steering joint seems happy with only a nominal mass. I was initially nervous of nesting lots of joints (I’ve ended up with quite a few), but ArticulationBody seems pretty forgiving.
I’ve seen Edy’s been implementing suspension and steering with ConfigurableJoint:

I think he was saying ConfigurableJoint rotations are solid, but linear springs are squishy, there was good discussion of it here:

I’ve found ArticulationBody linear springs to be good (vs ConfigurableJoint), but I’m not testing for the level or simulation fidelity Edy is.

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