robot vacuums - bump n go

hi there,
was considering to get a roomba but from this clip (flash link below) on their site it appears that the robots movement is similar to a bump n go battery
powered toy car,totally random movements.
it says it covers a given area in a room on *average* 4 times.thats like a car which drives forward then backward and covers the distance to work 4 times just to get you to the offic in the morning.mileage x 4
Why wouldnt they choose to make it clean the room in a systematic fashion? thx
http://www.irobot.com/sp.cfm?pageid4 Cleans whole floor
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beerismygas wrote:

If I recall correctly, they have a pretty small CPU, so they may not have enough memory to actually hold a room map. The key thing is that it is "hands off". You can do something else while it does its thing. For some people, this is an acceptable trade-off.
-Wayne
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I've never used one, but something I've read (or maybe something someone told me) left me with the impression you put it in the center of the room and it made a outward spiral pattern from the starting point and then it would bump and go around furniture and other complex features of the room. The outward spiral pattern is what made cover most the room in a fairly predictable pattern.
Is there a manual for it on-line on the web site? You might try reading it if it is. That would tell you more about it.
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Curt Welch http://CurtWelch.Com /
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The Roomba definitely has a more complex system than bump-and-go. It has an infrared sensor on one side, and the wheels have odometry from optical encoders. Some models have dirt sensors, and more recent upgraded ones have 'lighthouses" which help get the Roomba from one room into another.
The basic logic is to start from the center and sprial out, then to do a wall following routine, and finally do the bump-n-go. IF it detects a lot of dirt, it will continue to navigate in that area. It also has some logic to also help it get out of tight situations, such in between chair legs.
Regarding the mapping of a room; I don't think it was the processor or memory limitations that prevented this. Rather, it is the fact that odometry very quickly looses its accuracy, and can't be relied upon to vacuum a room.
There is a very in-depth group that discusses the Roomba at www.roombareview.com There is one section devoted to people hacking it. Some are working on methods of mapping a room and navigating it. The roomba has a serial port, which makes it hacker friendly. The lower end models are a good price for a robotics development platform. It think it is even better than the IRobot Create kit, because the Roomba actually serves a purpose.
Joe Dunfee
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cadcoke4 wrote:

That's about right. It has no clue where it is.
It's about time for SLAM to make it down to the hobbyist level.
                    John Nagle
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