[GeeTwo]

I can't access the document you referenced on the ieee site, even after trying a number of edits to your "quoted url", so this is a bit of a guess:

Ether's value for force Fc along the roller axis is correct, and is calculated from the torque applied to the wheel shaft and the radius of the wheel. If it were anything else, the torques around the shaft of the wheel applied by and to the wheel wouldn't be equal and opposite.wouldn't add up.

I suspect that the ieee document has a different definition for Fc, and possibly T and r. For example, T could be torque around the vertical axis through the center of the robot, and r could be the horizontal distance from the center of the robot r to the center of the wheel. Can you provide a cleaner link, or at least more solid definitions of Fc, Fs, T, and r as used in the ieee document?