You need some rotation sensors so that you can compare the rotational speed of the wheels and adjust the speed of the motors accordingly. There are even clever ways to do it with only one rotation sensor but it would be easy to do it with two.
You need some rotation sensors so that you can compare the rotational speed of the wheels and adjust the speed of the motors accordingly. There are even clever ways to do it with only one rotation sensor but it would be easy to do it with two.