Distance Measurment

Dose anyone have a recommendation for a distance measurment device that is good for longer distances. I’ve been playing around with several of the hobby grade sonic sensors. Although they work well within a few feet they are not really good for reading longer distances. Once my robot has entered a room I would like it to be able to read the total lenght and width of the room. From this I hope to define room identification tables so that the robot is self aware of it’s location. Any Thoughts?

Once you go beyond the range of IR and sonar (although there are some very nice sonars, if you go just above the “hobby grade”, like the ones from Polaroid) the only good option I’m aware of is laser rangefinding, and while sweeping laser rangefinders are getting smaller and cheaper (like this guy, a bargain at $2,600) they’re still way out of the normal hobby price range.

A lot of people fed up with the lack of a small, cheap, hackable, single direction laser rangefinder (please let me know if you come across one!) have been using the trick of looking at a laser pointer dot with a parallel, offset webcam, like this.

Of course, you can take this concept to whatever level of complexity you want, like my millibot friends here (lab-neighbors from when I was at CMU).

Good luck, and let us know what you come up with!