[GUI]

I think it wouldn't be too difficult to figure out if the robot is slipping. If you have encoders and an accelerometer you could compare the measured acceleration to the expected acceleraion at the measured output speed. If the measured acceleration is significantly less than what is expected, you would simply reduce the power to the motors. Does this sound like a good system (I haven't messed with any of the sensors in the kit, but this is what I assume would be the simplest solution).