Maglev idea a long time, is to use a magnetic floating object to overcome gravity to make, but really it is not easy, mainly because there is no stable equilibrium point. To achieve a suspension, the suspension must be stable. That is, with a force (or displacement) in any direction (up and down before and after, etc.) (small) perturbations are suspended solids, there will be a restoring force, so that the external force rebalancing undone.

I've seen levitation can be divided into active and passive two categories, the former such as feedback, with the optical, magnetic and other means to detect deviations from normal object is suspended suspension points, by adjusting the current to the electromagnet such that hold the object in the vicinity of the suspension point, requiring electricity. Such a suspension point of view from the truth, and the opening helicopter hovering no difference.