Numerical Integration Methods
I did some research into numerical integration methods and have posted the results of my experiments in a wiki page:
http://wiki.vdrift.net/Numerical_Integration
I’m not an expert on the subject, but from what I can see the NSV/Symplectic Euler/Euler-Cromer algorithm and the Velocity Verlet algorithms both look decent. Runge Kutta 4 is too complicated, too slow, and surprisingly isn’t even as accurate as NSV/Symplectic Euler/Euler-Cromer.
An additional finding, which I didn’t post in the wiki article, is that when manually adjusting the position of one end of the spring (such as when moving a wheel up because of an increase in ground height), don’t also set the velocity based on the position difference. Â This causes a weird over-damped response if you do.