how do u figure out the torque req'd to move a robot?

[Salik Syed]

Hi guys i've got a maybe simple question...
how does one go about calculating the torque req'd to move
a 130 lb robot with 6" wheels.... i know the whole force=mass* velocity
or whatever the heck they taught freshmen science doesn't seem right
... i mean what about friction etc.. i would think all of this goes into
the calculations....
btw i'm talking about torque @ the shaft not @ the wheel.although
i guess this can be calculated from the whole 3" lever arm distance or
whatever...

i don't know if its so simple actually.... now that i think of it.....