Even then, this seems like a poor choice of demonstration of visual recognition capabilities since you only need to read the initial state and then adjust it wh

Even then, this seems like a poor choice of demonstration of visual recognition capabilities since you only need to read the initial state and then adjust it when you make a move. They've used stepper motors which normally don't need feedback too, do movements can probably be done open loop. Perhaps they do only use visual feedback for determining the state, which would be a better demo, but I doubt anyone would be able know from that article!