When designing a robot it may help to consider where you think it might do its thing.

So here's perhaps an enumeration of robot working environments:

• entirely smooth vinyl, wood or concrete floor, indoor
• mostly smooth wood or tile floor, indoor
• typical indoor flooring, with transitions (smooth, tiled, carpet and rug)
• relatively smooth outdoor (concrete sidewalk, wood deck, parking lot)
• moderately even suburban outdoor (concrete, lawn, transitions, but no stairs, curbs, or cliffs)
• challenging suburban outdoor (uneven concrete, curbs, stairs, cliffs)
• wild environments (sand or beach, up in the mountains, tree branches, rocks, cliffs, anything goes)
• snow
• water surface
• water surface/amphibious
• underwater
• airborne
• outer space or other planets

There's also the notion of whether a robot can handle rain or spray. Or on a beach, can it avoid the waves?

See also: Robot Related Goals