Baby zorber

Babies benefit from exercise; parents don't benefit from constant supervision. How can these two be reconciled?

Put the baby in a small zorb on a concave roller bed (bed of ball bearings). It can crawl as much as it likes but it's not going anywhere.

Additionally, a circular screen around the roller bed, coupled with sensors monitoring motion of the balls, would allow the baby to explore a virtual world.

It may even be possible to generate a small amount of electricity from the movement of the ball bearings, which would help power the screen.