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The last part of your spring is the bumpstop.

HOW DO BUMPSTOPS WORK?

Bumpstops are an extra spring in the suspension system that deal with the highest compression area. They are available since v0.6.3.

To add bumpstops, you add 2 variables to your car.ini's susp<x> sections:

• bumpstop_len defines the length of the bumpstop (in meters), for example 0.07 (7 cm).
• bumpstop_k defines the maximum spring rate of the stop, for example 100000 (N/m).

The bumpstop is a non-linear spring, meaning its spring rate increases with compression. So the force itself will increase exponentially. The bumpstop will kick in when spring length = min_len+bumpstop_len. At that point the force is just 0. Once the spring length reaches min_len it uses its full rate (bumpstop_k).

Currently the bumpstop spring rate is linearly calculated from its compression.

TESTING THE BUMPSTOP

When designing the car's physics, set gfx.show_car_points to 1 (in racer.ini). It will show the suspension attachment point, plus the suspension line and also the bumpstop start as a yellow dot.

(last updated August 14, 2008 )