Subject:
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Re: Robot base
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 16 Feb 1999 22:46:06 GMT
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Original-From:
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Bill Richman <bill_r@inetnebr.com+SayNoToSpam+>
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Viewed:
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1553 times
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If you're looking for a reasonably large robot base, you might want to check
out "Toys 'R' Us"; there's a battery powered kid's vehicle called the "Wild
Thing" at our local store for $149. It's basically about a 3 foot diameter
cylinder about 1 foot tall, with a 6 or 8" motorized wheel under the left
and right sides, a battery, and a seat with some simple controls. You could
bolt a computer in the seat, wire up a couple of h-bridge motor drivers, and
be on your way. This would be particularly suited for an outdoor robot, as
it's a bit big and clumsy for indoors...
>
> Circular. It is harder to get stuck in corners with a round
> robot. It is easier to build a bumper system for it.
>
> > base dimensions: 9", 10" or 12" or larger
>
> 10", that leaves you a circumscribed square that is the size
> of a PC-104 type computer.
>
> > drive train configuration:
> > differential steering or combined drive and
> > steering or front wheel drive rear wheel steering.
>
> Differential drive is the easiest to solve the inverse kinematics
> for.
>
> One steered wheel and two driven wheels is the easiest one to
> get to go straight.
>
> One combined drive and steering wheel is the cheapest to build.
> (see the Hero-1, Hero-Jr)
>
> Three steered and driven wheels gives you the most flexibility
> and benefit (see the CMU rover papers)
>
> > drive wheel diameter: 2.75", 3" or 3.25" or larger
>
> 3.82" wheels for the following reasons:
> - Larger diameter gives better results over uneven
> terrain.
> - 3.82*pi = 12" circumference. 1 rotation == 1 foot
> of travel.
> Optionally 7.64" wheels
>
> > base material: plastic, aluminum or fiberglass (PCB material)
>
> Plastic (Polycarbonate aka Lexan) and aluminum. Alum for
> toughness and plastic that is easily worked, structurally
> sound and reasonably light.
>
> > accessories: turret, extra deck
>
> Extra deck that is a turret, slip coupler between the top deck
> and the mid-deck for signals.
>
> Anyway, it will cost about $300 to produce, it won't go up stairs and it
> won't include batteries and no one will buy it because it can't compete
> with a R/C on closeout from Radio Shack. :-(
>
> --Chuck
>
>
Bill Richman
incolor.inetnebr.com/bill_r
(Home of the COSMAC Elf
microcomputer simulator!)
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