[Jetweb]

well you basically you have two options from what I can see.

One is to just create an acceleration curve where you never accelerate faster than the surface allows, but then you will still slip in pushing matches, and will not be able to use the carpeted edges to there full potential.

The other option is to throw together a 5th wheel (extra un-driven wheel/caster) with an encoder on it and use it to gauge your actual speed and then limit your drive wheels to a fixed speed over the actual speed of the robot.

Personally i would chose #2 because #1 is almost useless, and option #2 is almost guaranteed to give you the best traction control for the amount of work it will take to implement.

There are some more extravagant solutions but I know I couldn't pull them off in 2 days.