The stall torque of the motor is 6.3 ft-lb. Two of these driving 6" wheels can generate a net force of 6.3 ft-lb x 2 x 12in / 1 ft / 3 in = 50.4lb. Unless you have a CoF of better than 1.25 and put all of the weight on those two wheels, you can't stall them with carpet traction. As you will probably be putting only half of the weight over these driven wheels (you did not mention any chains or belts to drive the other wheels), losing traction could be a real problem if you aren't careful. Several solutions exist to inhibit loss of traction, or to recover from it quickly. Any of these would also help reduce the chance of overheating. Ranked approximately from simplest to best the obvious ones are:
- limit the voltage ramp. That is, do not allow voltage to change by more than x volts in y milliseconds. This is the only "open loop" idea given here.
- monitor the current. Limit voltage increase to keep the current below a threshold.
- monitor speed using an encoder. Limit the angular acceleration. If you do this, you may want to make your joystick inputs be related directly to the target speed, rather than the applied voltage.