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Posted by Vaibhav Ghadiok on January 16, 2007, 2:35 am
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I would like to know if it is possible to reduce the cone angle of a
> SONAR or to make it more accurate for Ranging. I need this for Mapping
> Purposes. Two papers which do this using two SONAR's are
>
> The arc-transversal median algorithm - a geometric approach to
> increasing ultrasonic sensor azimuth accuracy (2003) Howie Choset,
> Keiji Nagatani, and Nicole A. Lazar
>
> Triangulation Based Fusion of Sonar Data with Application in Robot
> Pose
> Tracking (2000) Olle Wijk and Henrik I. Christensen
>
> Is it recommended to make ones ranging module or should one go for a
> standard module such as a Polaroid 6500.
>
> Any cheap LASER Rangers. I would define cheap as around $100.
> Here is a link I found where I could get some preliminary info
> http://www.seattlerobotics.org/encoder/200110/vision.htm
> Another paper I found for this was Low-Cost Range Sensing for Laptop
> Robots
> A. Davidson, B. Tribelhorn, T. Leung, and Z. Dodds (USA).
> Unfortunately, I am unable to access this paper.
>
> Any help would be greatly appreciated.
>
> Vaibhav
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Posted by RMDumse on January 17, 2007, 2:46 am
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Vaibhav Ghadiok wrote:
> I would like to know if it is possible to reduce the cone angle of a
http://www.robot-electronics.co.uk/htm/reducing_sidelobes_of_srf10.htm
--
Randy M. Dumse
www.newmicros.com
Caution: Objects in mirror are more confused than they appear
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Posted by John Nagle on January 23, 2007, 1:33 pm
Please log in for more thread options Vaibhav Ghadiok wrote:
> I would like to know if it is possible to reduce the cone angle of a
>>SONAR or to make it more accurate for Ranging. I need this for Mapping
>>Purposes.
Sure. Using Moravec's certainty grids as you move around will produce
an image with more resolution than the beam width. It's neat to watch
those images appear. I did that back in the 1980s.
It's also possible to go to much higher frequencies, like 1MHz,
and get a 2 degree sonar beam width. Cybermotion used to have a device
like that. The problem is that with a narrow beam width, you can't
collect data very rapidly; you only get one point per round trip time,
so scanning takes many seconds. So that's a dead end.
Hobby robotics sonars are still as dumb as they were twenty years
ago. One would expect better systems, with multiple sensors and a DSP,
but it's not happening.
Vision-based systems are starting to work; look up "Simultaneous
Localization and Mapping" (SLAM). Structured vision, like
triangulation-based rangefinders, is useful at short range.
True small-scale time of flight systems exist; see
"http://www.swissranger.ch". There's no reason that thing
needs to be expensive, although it currently is.
John Nagle
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Posted by Joe on January 24, 2007, 10:46 am
Please log in for more thread options I am curious to know if there are any low-cost [I.e. under $500]
phased-array sonar systems that are designed with a lot of on-board
processing (via a DSP). I mean something very roughly comparable to
the CMU cam, where a lot of functionality is built in. For sonar, I
can see the possibility of a system with 3 microphones and one emitter
that will send the user a simple 2D grid showing the intensity of the
reflected signal. Such a system may also provide the ability to do very
fast scans of an area.
Even if such a device is not available as a kit, perhaps a university
has documented such a project enough that an average robotics hobbiest
could put it together without know a lot of about digital signal
processors.
Joe Dunfee
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Posted by Joe on January 24, 2007, 10:24 pm
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> I am curious to know if there are any low-cost [I.e. under $500]
> phased-array sonar systems that are designed with a lot of on-board
> processing (via a DSP). I mean something very roughly comparable to
> the CMU cam, where a lot of functionality is built in. For sonar, I
> can see the possibility of a system with 3 microphones and one emitter
> that will send the user a simple 2D grid showing the intensity of the
> reflected signal. Such a system may also provide the ability to do very
> fast scans of an area.
>
> Even if such a device is not available as a kit, perhaps a university
> has documented such a project enough that an average robotics hobbiest
> could put it together without know a lot of about digital signal
> processors.
>
> Joe Dunfee
Hello Joe,
There is a company here in Massachusetts called Massa Corp, they build
phased array sonar imaging systems for the US Navy. Sonar is their
specialty. I am pretty sure they have a web site. You may want to
google for them and see if they also sell to the commercial market. I
am sure they would, just as a matter of doing business.
I know you can use an array (matrix, say 8X8 transducers or so) and get
an image. I don't know the exact details how. I figure, if I want an
image, I will just use a photo, or video cam (on land that is, I don't
know what your application is).
hth,
Joe
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> Purposes. Two papers which do this using two SONAR's are
>
> The arc-transversal median algorithm - a geometric approach to
> increasing ultrasonic sensor azimuth accuracy (2003) Howie Choset,
> Keiji Nagatani, and Nicole A. Lazar
>
> Triangulation Based Fusion of Sonar Data with Application in Robot
> Pose
> Tracking (2000) Olle Wijk and Henrik I. Christensen
>
> Is it recommended to make ones ranging module or should one go for a
> standard module such as a Polaroid 6500.
>
> Any cheap LASER Rangers. I would define cheap as around $100.
> Here is a link I found where I could get some preliminary info
> http://www.seattlerobotics.org/encoder/200110/vision.htm
> Another paper I found for this was Low-Cost Range Sensing for Laptop
> Robots
> A. Davidson, B. Tribelhorn, T. Leung, and Z. Dodds (USA).
> Unfortunately, I am unable to access this paper.
>
> Any help would be greatly appreciated.
>
> Vaibhav