Triple head wheels prototype

Golden had thought of triple head wheels on one of his latest drone. The system is used to stabilize the drone. Because of the bizzarness, I got inspired.
It has 3 drive on the back. Each drive active only if the ground on their layer is present. To do this, one of the proximity sensor in pair has to be close enough to touch the wheel.

Update:
Save energy! An automatic sensoring system, detect whether a ground is present. If there's no ground of that layer the wheel at that layer is disabled until each sees a ground.