Hal, a buddy of mine, and I were just chatting last night and we came up with the bud of an idea -- the Home Positioning System, or HPS. Yeah, it's a take-off on GPS (Global Positioning System), but for comparatively tiny areas like homes and offices.
Why do we need this? Well, we're going to see an increasing number of autonomous robots wandering around buildings and homes, and unless they develop some pretty awesome (and cheap) optical systems to help the poor things figure out where they are, some sort of highly accurate wireless navigation system will have to be developed.
One application that got us to thinking about this is Hal's new Roomba Discovery. You know, those cute little tortilla-warmer-sized robotic vacuums. We expect that in a few years, it won't be at all surprising for you to be able to program the Roomba to vacuum certain rooms on certain days, etc. Of course, that requires that the Roomba know which areas are called the Family Room, Living Room, etc. and it has to know where it is all the time so it can get there and back per the schedule.
One idea for the HPS we came up with is a wireless beacon system. Using some unregulated frequency, like 900 MHz, these beacons would send out a unique blip every few seconds. The beacons could be spread around the house, plugged directly into outlets or (and this is potentially very nifty) installed into the base of light sockets, between the outlet contact and the bulb base. Once the robot was trained -- what the floorplan looks like and where the beacons are relative to where walls, steps, etc. are -- it would be trivial for it to navigate wherever it needs to go.
Another idea would be to use RFID. By putting a receiving antenna on the robot and locating differently encoded RFID tags at each doorway or division (real or arbitrary) in the house or office, the robot would know when it's approaching a new zone. This doesn't work as well as a wireless HPS, but it does afford some of the same benefits and would likely be a lot cheaper.
The reason GPS can't be used for this is the issue of accuracy -- GPS is accurate to within yards, whereas an HPS would need to be accurate to within an inch or two. Also, GPS doesn't work as well indoors, as the satellite signals are harder to lock onto.
I'm sure we're not the first two guys to think about this, so what tech is out there to address this? Anything yet?
Follow-up: Apparently, somebody already thought of this back in 1999 and offered the idea of using X10 transmitters. Not a bad idea, but I think we can do better than that with today's, if not tomorrow's, technology.