Tiretestrig

[wyj1111kkk]

Hello, when using TiretestRig in Chrono to simulate tires and deformable surfaces, I output the slip ratio and found that the slip ratio calculation is only for braking conditions, i.e., s = wr/v - 1; whereas the slip ratio calculation when the tire is driven is s = 1 - v/wr. Here, s represents the slip ratio, w is the angular velocity of the tire, r is the tire radius, and v is the longitudinal speed of the tire. If I want to make modifications, where should I start?

[rserban]

There was a discussion related to this on the Chrono user forum (since people tend not to sign their posts, I don't know if that was you or someone else).

What I answered on the forum is that the definition of longitudinal slip is a matter of convention, as there is no universally accepted definition. In Chrono::Vehicle, we use the definition from SAE J670 (which is also used by other tools, such as Adams Car).

Here's a figure that shows the longitudinal slip with the formula used in Chrono, for different linear and angular velocities:

By the way, if you want to use a different formula, you can do so in the user-code, as you have access to all necessary quantities.