inexpensive wheeled base for otherwise humanoid bot?

In this month's Servo, in the "Menagerie" section, there is a picture of a cool-looking robot that's humanoid from the waist up, but on a
three-wheel base. It's inspired me; I'm thinking that something like that would be great for working the crowd at robot events, especially ones held in public places (malls etc.), where it could easily entice passers-by to stop in and see what's going on.
I've also long wanted to make an R2-D2-style robot, and have even gathered up some pretty powerful motors, but I'm totally stymied at building a chassis and mounting the motors to it, and wheels to the motors. I'm a software engineer; this mechanical stuff is hard for me, and the base seems to be the hardest part.
All this has me thinking: is there something I could cannibalize to make the base of such a robot? The one pictured in Servo almost looks like it might be such a stock item (or if it's custom built, it's very well done!). I've poked around, and looked a bit at motorized wheel chairs and golf caddies, but neither seems quite right. Is there something else I should consider?
Thanks, - Joe
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If you can find an affordable motorized wheel chair I would go for that for the simple reason it already has the motor control circuits that can be the hard part for someone with limited electronics skills to put together.
-- jc
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I bought a used wheel chair from eBay. About $200. But then I found it needed replacement batteries, and there's about $250. Ugh.
But they're still quite a deal. I think SS must buy you one new for free, because the market for used ones is very depressed. Why buy a used one, when you can get a new one "just for qualifying".
I haven't gotten very far in conversion, but they do make an interesting base. Potential range is ~25 miles. Very stable. Quiet operation. Chargers built in to most models. And of course, most public buildings are already modified to accomodate them access.
Randy www.newmicros.com
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We must NOT make robots that mimic
human movement . unproductive .
we . instead, use their best abilities .
Robots need 220vac extension cords
to be productive . forget the batteries .
The future is competition , if your
robot can't compete , your reputation
is lost , along with your employment .
By 2020 , there will be no cars , nor trucks
on the roads . Electric trains will do ALL
transport .
----------------------------------------------

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The electronics I can handle. It's the mechanics that are killing me.
Thanks, - Joe
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...

Ah. That should just make things more interesting! :-)oo
I've been working on HEADS (animatronic - sort of) and find the artistic part the most difficult/interesting.
I started with my own sculpture but ran into so many problems that I decided, at least for now, to use a hairdressers mannequin instead.
In the meantime I learned a lot about moldmaking, facial expressions and sculpture.
A bit more on my web site under builders log.
DOC
Have robots. Will travel. http://www.robot-one.ca
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snipped-for-privacy@sympatico.ca wrote:

I looked at your log (http://www.robot-one.ca ) -- the MyDummy project is very cool.
And you've brought up another thing I've been thinking about too: what to use for a head? I know I don't want to sculpt one, but then, I'm not going for humanlike -- only humanoid. Ideal would be something like a Motocross helmet with a dark visor, so I can put lights behind it for the eyes. But helmets are heavy (and tend to be on the expensive side, too), so I'm considering other approaches.
You can get styrofoam wig stands that have a nice shape: clearly not trying to look realistic, but still clearly humanoid. Something like this: <
http://jojo-estore.com/images/styrofoam/faceless.jpg
...but I'm not sure exactly how I'd go about turning this into a robot head. I really need something hollow, because I plan to stuff it with servos and other electronics. But maybe I could use this head as a form for a mold, or drape thermo plastic over it, or some such? Has anyone successfully made a robot head or faceplate from something like this?
Thanks, - Joe
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