[Gui Cavalcanti]

After a week of robot camp, a couple of months searching around FIRST sites, and a few weeks at competitions, I still haven't found anyone who can link this all together for me: what is the link between friction, traction, and torque?

First off, torque. Motors have a neat, pretty little 4-line chart saying "if my motor is moving at this rpm it's generating this torque which is so and so efficient pulling this much current at 12 volts". I understand the individual bits and pieces of it, and how they all connect, but what I don't understand is how you use it. Do you calculate the torque of your machine and then gear to that? Do you calculate the speed of your machine and then gear to that? How do you get to "peak torque" on a robot?

Related to that is how on earth do you link torque to moving your robot? Granted, the little 4-line charts mentioned earlier will tell you your torque at certain conditions, and I assume you scale up torque through gearing and mechanical advantage systems (arms, etc). However, how is torque related to moving your drive train and your available pushing power? Where do friction and traction fit into these calculations?

On the note of friction and traction - I've heard a lot of teams pulling the "f = uN" stunt recently. That doesn't work. Tell me if this logic is correct - carpet is not a surface. It's a conglomeration of threads strung together, and so you can't accurately test any sort of friction. Also, if you have things like file cards (which have next to no traction on any other surface) they dig into the threads and latch on, and don't really count as traction...

Now, static friction I can see coming into account from a wheel turning. However, how do you calculate this on a robot? Do you disengage your motors and pull your robot across a carpet on a spring scale?

Any answers to these questions would be greatly appreciated, as well as the random comment of "hey, that question has nothing to do with it, what are you talking about?"

Thanks!