Anyone have a quick fix to keep pacejka physics from skittering around while stopped due to rounding?
Or rather - I guess the issue is forces going to 0 and velocity approaches zero.
The problem you’re seeing isn’t so much to do with pacejka formulas but rather that slip ratio calculations aren’t well defined around zero velocity which causes oscillations and instability in your tyre updates. This is a common problem with vehicle simulations and unfortunately there isn’t really a ‘quick’ fix for it.
You can try to combat the problem by using a better integrator such as RK4 or increasing the number of iterations of your tyre update loop with smaller time steps or perhaps by introducting a damping factor into you tyre updates at low velocities. Likely you’ll want to experiment with a combination of these things to find the best results for your simulation. Alternatively you can try to sidestep the issue, when at low speeds you could try swapping to a different tyre model that isn’t dependent upon slip ratios.