bullet dynamics

[joevenzon]

The problem with the suspension force is that we are mixing internal and external forces. The suspension force is an internal force acting between car chassis and wheel. It should not change the kinetic energy of the car(like car accelerating with zero driving torque). The only external forces acting on the car are the gravity, normal/friction forces at the tire contact patches and the aerodynamic drag. I've fixed it in the bullet branch. Should I patch the trunk too?

Only if it's a really quick fix.

I'd like to have the wheel camber depend on suspension geometry given a vertical wheel displacement. I don't know how to achieve it with the hinge model. I am not a Mechanical Engineer, so maybe I am missing the mark here. I will look for some suspension model papers.

Just thinking out loud here. There are a number of properties that change as the suspension is deflection: wheel position, spring force, camber, toe, damping, etc. Defining a hinge point makes it possible to model some wheel position change as suspension is displaced, but it's limited to an arc path. We allow changing spring force and damping with displacement by using linear interpolation (see the XS.car's spring-factor and damper-factor settings). We treat the camber and toe as constants. Since these are all functions of suspension displacement, it'd be easy to model camber, toe, and even wheel position by defining points and linearly interpolating over them, like we do with spring force and damper force. Using this I think we could simulate the widest possible range of suspension configurations.