Subject:
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Re: Mechanical question
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 26 Jul 1999 21:03:14 GMT
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Viewed:
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834 times
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I was wondering the same thing until a little while ago, I saw a large
(i.e. industrial-sized) remote control vehicle in use by the UK fire
service to fight fires in hazardous areas. The vehicle uses solid low-
grip rubber tyres and four wheels that are narrow track, but large in
diameter compared to it's wheelbase. something like this:
##### #####
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##### #####
I thought about this for a while then knocked up a Mindstorms 'bot based
on the same idea, using the wheels from an 8828 (There are loads of
other sets with the same wheels) set close together with a two motors on
each side wired together, one driving each wheel (geared 1:1) . This
arrangement gives reasonable torque, and plenty of speed. Works a treat
over deep-pile carpet that used to get caught in tracks, and is much
faster than a tracked vehicle over more solid terrain such as lino or
short-pile carpet.
I use it as a basic 'proving ground' chassis for software
locomotion/detection ideas. After some experimentation I discovered that
the wheels don't have to be that close together, just that they have to
'slip' in the right way.
Regards, Dave.
In article <379CB3DA.5EFD55F4@midnightbeach.com>, Jon Shemitz
<jon@midnightbeach.com> writes
> I've been puzzling over this one, and I still don't really understand
> it: Why can a bot with tank treads do a turn in place, while a bot with
> four wheels geared together so that the front and back wheels on each
> side always move together can not? My *expectation* was that the two
> were basically identical, but that clearly is not the case. The 'tank'
> turns easily; the 'car' just sits there making motor straining sounds.
>
> Is it that the tank treads are harder rubber than the tire wheels, and
> so resist sideways motion less?
>
> Or is it that the wheeled version is concentrating all the sideways
> force at four points, while the treaded version is spreading the same
> force over a much larger area?
>
> Or is it something else entirely?
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--oOOo-----U-----oOOo------------------------------------------------------
| Dave Ryder DaveR@ansuz.nospam.Demon.co.uk (Remove .nospam to reply) |
| ...I'm sorry, Dave, I'm afraid I can't do that... |
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Message is in Reply To:
 | | Mechanical question
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| I've been puzzling over this one, and I still don't really understand it: Why can a bot with tank treads do a turn in place, while a bot with four wheels geared together so that the front and back wheels on each side always move together can not? My (...) (25 years ago, 26-Jul-99, to lugnet.robotics)
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