ultrasonic sensor for wall following

Hi all,
I'm looking to do wall following with my helicopter and was hoping someone could suggest an ultrasonic sensor that is lightweight and
efficient. I'm currently looking at Devantech's SRF08. Can anyone comment on whether or not they think this is the best sensor for the job? To be safe, I'd like to remain 3 feet from the wall.
Thanks in advance, -weg
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snipped-for-privacy@drexel.edu wrote:

I would think that one of the Sharp IR distance sensors would be a good choice. The Mark II store has several versions. Some put out an analog signal for the distance. Others simply trigger if it detects within a certain range. Note that is not simply a light sensor. It actually puts out a spot of light, and focuses the image of it reflecting from the surface onto its linear sensor. So, parallax is the method used. The LED output is modulated, so it has good noise rejection as well.
There are several models with different ranges and outputs. Here is one, the Sharp GP2Y0A02YK. It has a 150 cm range with an analog output http://www.junun.org/MarkIII/Info.jsp?item 
I just noticed they have a minature version...http://www.junun.org/MarkIII/Info.jsp?item but it may not have enough range for you.
Joe Dunfee
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Oops, that link didn't' work right. The minature one is http://www.junun.org/MarkIII/Info.jsp?iteme
Joe Dunfee
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If you don't mind, can you explain why you think IR sensors will work better than sonar in this application? Don't IR sensors provide different readings depending on the reflectiveness of the surface?
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snipped-for-privacy@drexel.edu wrote:

There are simpler types of distance sensors that work on reflectiveness, but the particular Sharp sensors I referenced were of a different category. They work on a parallax method. A LED outputs a modulated light focused through a lens. A second lens focuses a view of the world onto a sensor which essentially detects where the dot is seen (not really a linear array, but functioning like one).
So, it works on a parallax principal, not reflectivity. It has proven to be a very robust sensor from the standpoint of rejecting ambient light, and varying colors of surfaces. Of course, there are problems with reading highly reflective surfaces or things like glass.
Joe Dunfee
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wrote:

You might get some interesting interference from the rotor blades whizzing about if you're planning on using sonar. How about a laser rangefinder? Regards, John Ebbinghaus
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Know of any that are light in weight (<20 grams) and still reliable?
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