Subject:
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Re: Acroname robotics...
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 21 Mar 2000 18:48:28 GMT
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Original-From:
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Will Bain <willb@selway.umtNOSPAM.edu>
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Viewed:
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2247 times
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Bob Kelly wrote:
>
> I am looking to buy a Handy Board, Expansion Board, motors, GP2D12 sensors,
> Polaroid 6500 instrument package, and maybe the Eltec sensor. I will likely
> use Acroname, as they appear to have pretty good prices and I can save a few
> $$ on shipping.
Acroname certainly seems to be the best source for the GP2D12 and Polaroid sonar.
> Has anyone built from the Acroname kits? Can I have some comments,
> pros/cons, things you were pleasantly/unpleasantly suprised about, etc.? Is
> there kit as complete as you expected? I've never built a kit this ambitious
> before (the most I've ever done is the object detector from Lynxmotion) and
> want to be sure it is as fool-proof (I AM a fool, after all) as possible.
I'm a fool, too. That's why I went with the fully assembled & tested Handy Board from Patrick Hui. The only things I had to add were the NiCd battery and fuse F1 from Digikey.
> I have used the GP2D02 before, but I only used one and it worked great once
> I figured out how to get linear output from non-linear readings. I wish to
> use at least five GP2D12s with the expansion board , as you can run as many
> as eight by cutting only one pullup resistor trace on the Hboard (I'm
> thinking of addidng a switch instead of just cutting it). Also, there is no
> software overhead required. What has been the list's experience out there
> with the GP2D12s? Is it as easy to interface as advertised? Does it still
> have non-linear output values for a linear change in distance? Is cutting
> the trace all that is truely required?
I was just looking at the Sharp GP2D12 specs on-line the other night. According to the graph, the signal/distance curve is sort of logarithmic. Still, unless you're mapping, the exact distance doesn't really matter anyway; might as well write your code to make use of the raw (non-linear) values. Supposedly, you cut the pull-up resistor trace for port 0, and that's supposed to float all eight analog ports on the expansion board. Sounds too simple, eh?
> I would like to construct the base out of some sort of light plastic. I used
> the Lynxmotion 1/4" stuff before and it was great, but it was expensive.
> What is an easily machined (with a small band saw), easily drilled,
> super-glueable, lightweight, strong, stiff, and inexpensive material? What
> are your favorites if you don't have access to machine tools? I would love
> to use aluminum and really have a nicely done 'bot, but that appears to be
> beyond my means.
I plan to use thin, clear Lexan (or some other brand of polycarbonate). I would like to find a plastic bell jar and screw a flat disk into the bottom of it, with holes cut for the wheels. I even thought about lopping off the top and then reattaching it with a plastic "lazy susan" bearing and servo motor, so that I'd end up with a small, clear plastic R2-D2 shape with a dome shaped turret for a head. That's where I'll put the sonar and the video camera/transmitter. There's a plastics shop here in town that has a solvent glue specifically for use with polycarbonate. Until I graduate and have some free time though, I'll just have to make do with my Legos.
> What other sensors that are very funtional, but relatively inexpensive do
> some of you find to be a good addition to the capabilities of your 'bots? I
> know I will be adding the Hamamatsu IR emitter /detector pair for wheel
> encoders, and some simple light sensors. I would really like to make a very
> functional 'bot that has a wide range of capabilities to experiment in
> software with.
I figure a color detector would be generally very useful. Some on this mailing list have been experimenting with arrays of light detectors and color filters. For ideas on what fun to have with a color detector, check out Sony's Aibo robotic dog. It can be "taught" to prefer objects of certain colors and disdain others.
Best of luck!
-- Will
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