Watch the video by smarter every day, he has a good explanation of it, but essentially each section moves a small amount before it mechanically flips a switch in the next one which tells it to start moving and for the previous section to stop moving, this chain of small movements propagates up the sections ending in the centre, then the outer section is ‘told’ to start moving again, So there’s no need for precise calculations of how far each wheel has to travel, instead the wheel will travel far enough to flip the switch and then stop and the further out they are the further it has to move before the switch flips
