Wheeled vehicle with steering, simple suspension?

[lucasw]

Currently I have a cuboid with rounded edges for a collider and apply force to the center to drive it forward and make it off center to turn (https://github.com/lucasw/bevy_viz/blob/main/vehicle_avian/src/bin/vehicle.rs#L127). It doesn't behave well on turns though, it acts like a hovercraft.

Is it possible to set friction to different values for different direction (I think bullet and others allowed this), so it slides forward and backwards easily but is resistant to shifting sideways? I suppose I could calculate forces to resist sideways motion and apply them every update, but it seems like that would be less stable than a lower level lateral friction value and always a timestep late, counteracting the slipping of the last update.

I'm okay with using ray casts for suspension, but a few experiments with this using apply_force_at_point depending on how close a corner of a cuboid is to the ground gets me a lot of pitch and roll oscillations even at a standstill- possibly I just need better damping on the suspension springs.

I'll likely try revolute joints with wheels next, and stick to slower speeds so high wheel rotation rates isn't an issue. (https://github.com/Jondolf/avian/blob/main/src/interpolation.rs#L141 'Very high angular velocities (ex: for car wheels or fan blades) can be especially problematic').

Springy balloon-like tires could be fine instead of a more realistic suspension.

If anyone has a working example to share I'd really like to see it.

[lucasw]

I tried making capsule wheels (exaggerated here to make the capsule orientation clear), but they tend to explode when I attach them, or even if that is avoided they change orientation (in the first picture the initial and desired orientation is shown, with no joints between the bodies, in the second picture I've managed to attach a revolute joint between the chassis and wheel, but the capsule orientation is rotated from where I initialized it- do I supply the orientation somewhere else, it doesn't care where I create it?