# Car rotation as a function of speed

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I am making a car sim (go to this thread to check it out). Now I have a function to rotate the car by a fixed angle. How do you model the rotation as a function of speed. eg. the car should not rotate at all when speed = 0, also rotate lesser and lesser as speed increases. In the demo, I have used a simple parabolic function, but I'm not satisfied. Any ideas?

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I just wanted to clarify something. When you say "rotating" do you mean the car is turning as in normal driving, or is it spinning, i.e. out of control?

-Josh

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The angle (in radians) is simply velocity/radius. That assumes that the car doesn't slide.

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the centre of rotation of a car depends of the steering ange, and the wheelbase. the rate of turn, or angular velocity is then simply W = V / r, r being the turning radius, which can also be calculated when you calculate the centre of rotation.

//      wheelbase//     <------->//            ---      Velocity//      /      |      <------//     / ------|   ^//    /  \    ---  |//        \    |   |//         \   |   |  radius of turn//          \  |   |//           \ |   |//            \|   v  //             O Centre of rotation//////

I let you work it out, it's just trig.

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Thanks for all the replies! But oliii, before I saw you post, I had devised something like this:

static friction balances mv^2                         ----                          R                          (R is the turning radius)So R = k * v^2 -> I am writing here:R = Rmin + k * v^2    Now in a circle delta_theta = delta_l / R = v * dt / R;       Therefore, delta_theta =     v * dt                         --------------                         Rmin + k * v^2

Seems to work alright. Let me know what you think ...

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