When I read about Segway I always wonder how such precise control over the wheel motors can be achieved.
I mean if the rider wants to go one foot forward, then one foot back, he leans forward, the motors start rotating the wheels, then he leans back and the motors change direction instantly and then when he's back he stands straight and the motors stop.
Again, to achieve balancing motors will rotate in perfectly controlled manner at whatever speed is needed to balance the Segway.
From my experience with electric motors found on various stuff like power tools and sewing machines those are pretty hard to control precisely. For example, when a variable speed drill is started it just accelerates at whatever rate and actual rotation rate will largely depend on the load - whether I drill wood with a 2 millimeters bit or hard steel with a 10 millimeters bit.
How do systems like Segway achieve such precise control over electric motors?