bullet dynamics

[NaN]

Status report:

I failed to setup a constraint based suspension.
Getting the hinge stiff enough to carry a 1500 kg chassis with 9.81m/s^2 gravity is a problem. Increasing the number of iterations in the constraint solver from 10(default) to 40 has shown some improvement. But I am not sure if we can afford to run it at this speed. More testing is needed here. The values for the spring constants had to be unrealistically high(like one order of magnitude above the real world value). I may have messed up this one using a angular spring constraint. The usual tuning tips have been to adjust inertia, masses till the simulation looks plausible. So I think bullet is not meant for physically correct simulation.

So I rolled back to wheel ray simulation. It currently has two bugs to be fixed:

1) The car oscillates around vertical axis when at rest due to tire friction. It is not visible, but it manifests as oscillating slip values. Thats why the TCS is causing problems with some cars(360). Not sure how to fix.

2) Because the wheels are following the surface we have very fast wheel displacements (0.01m/ms => 10m/s) from time to time. At such displacement speeds the shock absorbers determine the suspension behavior completely. The damping forces can exceed 100000N with spring forces of about 7000N at the same time!!! The problem is not that pronounced in the trunk. It might be related to the track collision object in the branch. Not sure what fails here. A quick fix would be to either clamp the displacement velocity or decouple the wheels from the surface(wheel stiffness).

As soon as this issues are resolved(or worked around) I am going to merge the branch back. So that we can release it.