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Unread 09-01-2009, 10:16
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Re: Implementing Traction Control for an advantage in the 2009 game

All,

Warren is absolutely correct in that my analyssi did not include the dead weight of the trailer. The robot still has to accelerate the trailer, but you also get some tongue weight transfer. The actual equation break down is like this:

F = (Mrobot + Mtrailer) * accel

Ff = (Mrobot + Mtongue) * g * Mu

Setting both sides equal to each other and simplifying:

accel = (Mrobot + Mtongue)/ (Mrobot + Mtrailer) * g * Mu


Let's assume tongue weight is negligible (it is actually really small). The equation breaks down to:

accel = Mrobot * g * Mu / (Mrobot + Mtrailer)

Our estimation of a trailer weight of 40 lbs and a robot weight of 150 lbs (120 + bumpers + battery) puts us at 150 / 190 so the accel is:

accel = 0.79 * g * Mu

Warren's estimate was pretty darn good at 75%. If your robot mass is less, then your ratio gets smaller and you will have a lower available acceleration.

This analysis assumes all of your robot wheels are driving. If you do not have all of your wheels driving, then you will have to decrease your acceleration even more.