Tuning PID Constants Over a Range

[Jared Russell]

Originally Posted by Ether

For a robot with center of mass located at center of rectangle formed by the 4 wheels, I think that should be:

S = (1+f²)(W/2)ω

S is drive wheel linear speed
W is trackwidth
ω is desired turning rate in radians per second
f the the ratio L/W, where L is wheelbase

Yep, and this is the equation we actually used as our starting point (using the track width and wheelbase length of our inner four wheels). Our CoG was within an inch or two of the geometric center (ignoring dynamics). We found that even with this correction, we were ~50% off of the true value (a bit unsurprising since even though our outside wheels were raised, they still bore some weight because of deflection of our 15-20 PSI inner wheels).