Gearbox friction model

[Ether]

Originally Posted by IKE

For your model, you will then have:
Torque out=eff*ratio*input_torque-c*speed^2

The above is essentially what I used in the Drivetrain Acceleration Model, except that instead of c*speed^2 I used Kro+Krv*speed (line 85 in the C code). This one line of C code is easily changed to make it whatever function of speed you like. In FRC drivetrains, the Kro constant term is probably needed since even at very low speeds and output torque there is friction in the drivetrain (due to tension in the chains/belts, misalignment, etc).