[epzrfudk] Spherical wheel

Imagine a spider walking on a sphere; the spider's adhesive feet grip the sphere and help it move along.

Now, imagine holding the spider in place at the top and allowing the sphere to freely move underneath it.  The spider's feet cause the wheel to move underneath it. The adhesion may have to be a lot stronger.

Build this as a mechanical spherical wheel.  The adhesion may be done mechanically (the "spider" has grippers that grab knobs on the surface), or electromagnetically.  This is an "active" contraption, needing to track the sphere and grab an release knobs very rapidly, vaguely similar to an optical mouse.

The inspiration, perhaps first application, is a handheld massage roller toy where the knobs also stimulate the skin as they roll over.