Robot position sensing

How creative are you?
Just for fun, I am putting together a list of every known way that an indoor robot can tell where its absolute position in a room is.
I am excluding relative position solutions such as wheel odometers unless someone can show that they don't drift. I will post a summary of all the answers when the ideas stop coming in.
Here is my start:
Ultrasonic range finders pointing in all directions.
Follow a line on the floor made with UV ink.
Use a camera and figure out where you are from what it sees.
Three bike reflectors on the ceiling, and a scanning beam of light with a photodetector to see the reflections.
Optical mouse technology, looking at the floor or at the ceiling (or does this technology drift?)
Any other ideas?
--
Guy Macon, Electronics Engineer & Project Manager for hire.
Remember Doc Brown from the _Back to the Future_ movies? Do you
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I like a rotating IR sensor stalk with at least 2 beacons in the room, each modulated uniquely, more if there are obstructions or hallways. With their known positions and the angle the sensor was at when it 'saw' each one you can calculate your location in the room(s) easily.
"Guy Macon" <http://www.guymacon.com wrote in message

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Optical mouse technology drifts.
How about barcoded floor tiles. "Guy Macon" <http://www.guymacon.com wrote in message

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Lots of interesting ideas so far!
Here's one:
Send an omnidirectional ultrasonic pulse out from the robot. Pick it up with an unidirectional ultrasonic microphone (probably the same transducer) you will see a pattern of weak echoes from the walls, from the two sided (wall meets wall, wall meets ceiling) corners and from the two sided (wall and wall and ceiling meet) corners. Process them and try to figure out the geometry of the room. That tells you where you are, but not where you are pointed. For that, add a cheap electronic compass. or simply measure- move-measure.
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Are we *sure* that optical mouse technology slips? Yes, the mice you buy slip, but they have a 16x16 pixel CCD with two possible output levels (bright/dark). I suspect that a 64x64 matrix with 256 levels would be able to track the pattern going under it without slipping - especially if you kept in the robot's memory a virtual 1024x1024 image with the present "mouse" image centered in the virtual image. (The areas that the system hasn't seen yet will be blank, of course...) I suspect that such a system could keep track of it's position without slipping.
-- Guy Macon, Electronics Engineer & Project Manager for hire. Remember Doc Brown from the _Back to the Future_ movies? Do you have an "impossible" engineering project that only someone like Doc Brown can solve? My resume is at http://www.guymacon.com/
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Guy Macon <http://www.guymacon.com says...

Info on optical mouse technology:
http://prism.mem.drexel.edu/stanciu/Web_page/optical_mouse.htm http://www.bytesector.com/reviews/id-165/mx_optical.pdf http://www.labs.agilent.com/news/2003features/Gordon_optical_nav.pdf http://literature.agilent.com/litweb/pdf/5988-4289EN.pdf http://www.labs.agilent.com/news/2001features/fea_optinav.html
Could it be that the slippage is all in the internal image to quadrature pulse algorithm, and that we can get an absolute position by processing the image externally?
--
Guy Macon, Electronics Engineer & Project Manager for hire.
Remember Doc Brown from the _Back to the Future_ movies? Do you
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The optical mouse, ( assuming the agilent products, ) has a 16 by 16 array at 6 bits per pixel. A digital camera, calibrated to read surface features, could correleate image shift to distance traversed. a sophisticated algo could even account for rotation.
The optical mice are pretty slow for direct image transfers, so mapping them into memory is pretty much out of the question, for the amount of data that you get.
My tests have shown a certain amount of drift between the quad output and real position. Look forward to the April or May issue of Nuts N Volts, where I cover the mouse hack in detail.
Mike "Guy Macon" <http://www.guymacon.com wrote in message

Doc Brown from the _Back to the Future_ movies? Do you have an "impossible" engineering project that only someone like Doc Brown can solve? My resume is at http://www.guymacon.com /

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Hi Folks,
Any pointers to the "cheap electronic compass" reference?
Thanks, -KC.
Guy Macon wrote:

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Hi Folks,
Any pointers to the "cheap electronic compass" reference?
Thanks, -KC.
Guy Macon wrote:

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: Hi Folks,
: Any pointers to the "cheap electronic compass" reference?
http://www.robot-electronics.com /
--
==========================================================
Chris Candreva -- snipped-for-privacy@westnet.com -- (914) 967-7816
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http://www.dinsmoresensors.com /
Cheers!
Sir Charles W. Shults III, K. B. B. Xenotech Research 321-206-1840
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This is a multi-part message in MIME format. --------------1D38759A8A39005611249C44 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit
I like using a radio direction finder.
A 4 antenna receiving device gives the bearings of two or more transmitters as the robot moves around.
Ramsey kits makes a nice one its a TDOA for about $150
Guy Macon wrote:

--------------1D38759A8A39005611249C44 Content-Type: text/x-vcard; charset=us-ascii; name="svorres.vcf" Content-Transfer-Encoding: 7bit Content-Description: Card for steve vorres Content-Disposition: attachment; filename="svorres.vcf"
begin:vcard n:Vorres;Steve tel;cell:619-890-2287 tel;work:858-385-5030 x-mozilla-html:FALSE adr:;;;;;; version:2.1 email;internet: snipped-for-privacy@lsil.com title:FAE Manager Wireless,High Speed I/O , DSP fn:Steve Vorres end:vcard
--------------1D38759A8A39005611249C44--
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Do you mean the DF-1 Foxhound?     http://members.aol.com/homingin/ramsey.html It looks like it's not trivial to get running.
Here's one with RS-232 output.     http://www.silcom.com/~pelican2/PicoDopp/PICODOPP.htm Same price for an assembled tested unit.
(I'm interested in something much more limited - two antennas and a tethered transmitter.)
--kyler
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A single rotating ultrasound ranger with a geared motor turning it or a couple of hall sensors on the stalk so it stays calibrated. As it turns, it generates a map of the room based on how far walls are from it. If you can control the room (eg, it's your living room, put an infrared diode on one wall (and an infrared receiver on the ultrasound stalk) so it always knows which wall is which. I suppose a compass might work too...
Same would work using a laser rangefinder, of course, or radar.
Let's see... let's come up with something a little more rube goldberg'esque. How about a rotating antenna wave guide that tracks RF interference from your electrical equipment and maps its position based on how much interference it's getting?
Or..... You could use the optical mice technology and periodically calibrate for drift by firing a suction cup in all directions and winding in the thread until you get tension (so you can measure the string). :)
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Now THAT'S what I call "creative"!!!
The mental picture of the suction cups firing...
That RF idea is really quite elegant. Would it lose it's way when you turned off your PC?
--
Guy Macon, Electronics Engineer & Project Manager for hire.
Remember Doc Brown from the _Back to the Future_ movies? Do you
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Guy Macon wrote:

You could use this mapping paper as floor material: http://www.wired.com/wired/archive/9.04/anoto_pr.html
Mitch Berkson
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How about accelerometers/gyros to get relative motion, with absolute positioning updated by GPS? OK, so this is for a room the size of the AstroDome...
In conjunction with images of the walls and dimensions of the room in the robot, use cameras for orientation and ultrasonic range finders to triangulate.
Bill
"Guy Macon" <http://www.guymacon.com wrote in message

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If all you need is a complete very very exhaustive list check out "Sensors for Mobile Robots" by H. R. Everett, AK Peters, Ltd. 1995 I even think you can obtain the book for free (as a PDF) online somewhere.
Keep in mind that it covers all the different concepts and most of the variations/combinations of some really expensive sensors but it might give you ideas.
Later,
Guy Macon wrote:

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=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Stephane Gauthier
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Thanks! I will order the book.
As for what I really want, I want an interesting discussion in the comp.robotics.misc newsgroup, and maybe a few ideas I hadn't thought of before. I am getting plenty of both.
Here is another idea: Make a paint that is clear in the visible range but when hit with a red light fluoresces in the infrared range. Scan for it with a red laser that has an IR detector pointed in the same direction as the laser. Paint a few invisible marks that only the robot can see on the ceiling.
--
Guy Macon, Electronics Engineer & Project Manager for hire.
Remember Doc Brown from the _Back to the Future_ movies? Do you
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Guy Macon wrote:

Guy:
You might want to read Borenstein's "Where am I?" paper. Here's a URL that contains some interesting references:
<http://gramlich.net/projects/robobricks/laser1/rev_b/index.html#References
By the way, the references come from some work I did with laser triangulation based on some work done by Jim Ubersetzig.
Hope this helps,
-Wayne
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Overview: http://www-personal.engin.umich.edu/~johannb/position.htm
Long PDF (282 pages): [ http://www-personal.umich.edu/~johannb/shared/pos96rep.pdf . ]

This is really good information. Thanks!
--
Guy Macon, Electronics Engineer & Project Manager for hire.
Remember Doc Brown from the _Back to the Future_ movies? Do you
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