Subject:
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Re: Mapping
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 15 Dec 1998 15:31:32 GMT
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Original-From:
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Tom Brusehaver <TGB@nospamCOZY.WAMNET.COM>
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Reply-To:
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tgb@wamnet.comSPAMLESS
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Viewed:
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1244 times
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> Identify the characteristics of your sensor
> The sonar we are using has a detection cone of about 40 degrees, this
> depends upon the texture, material, shape, and size of the obstacle. A
> flat metal surface directed straight back at the sensor broadens the cone
> to about 60 degrees up close (1.5' to 5' for the Polaroid sensor). And
> narrows the cone to about 2 degrees at very far distances (about 22' for
> the Polaroid) because nothing else is detected at those distances. The
> surface used was 12ga steel 1'x1' smooth plate. Other obstacles were kept
> out of it's line of vision. ~2msec / foot of distance according to the
> oscope used. A person on the other hand could only be detected out to
> about 7'.
Watch the critical angle for the sonar too. If the sonar doesn't hit
almost straight on, some of the energy will be reflected off at an
angle, and may provide false longer distances. Smooth surfaces will
have a lower critical angle then coarse surfaces.
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]< <------------>| wall
sonar |
straight on good measurement
]< <-
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Angle reflection longer measurement.
Good mapping will take a combination of sensors, and actual wandering
of the room to detect all obstacles and make an accurate map. Decide
your grid size, and program the robot to get to each size area, and
mark the grid as open or filled.
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Message has 1 Reply:
 | | Re: Mapping
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| Thanks for the tip on reflection error. I'll have to build in a function to weight the position accordingly. I'm trying to stay away from occupency grids and use the native vectors to conserve memory while maintaining accuracy. I may have to resort (...) (26 years ago, 16-Dec-98, to lugnet.robotics.handyboard)
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Message is in Reply To:
| | Re: Mapping
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| I've just started experimenting with mapping and these are my thoughts on it. Drop the robot anywhere in its environment. The robot has a sonar hooked to a servo so the sensor can be scanned horizontally. As the sensor sweeps from left to right, (...) (26 years ago, 15-Dec-98, to lugnet.robotics.handyboard)
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