[nuclearnerd]

Now if you really wanted to go gung ho with this design, drop one wheel and driver it with an actual differential. The housing could be bolted to the chassis, and the rotation of the module could be set by the relative speed of each motor, with gear teeth, rather than carpet, to push against. It's still not going to work well, but it's closer!

(the response for steering is way faster than the response for speed, so unless your drive acceleration is very slow, it will be difficult to keep the steering controller from over shooting.)