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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Tue, 27 Jul 1999 22:30:22 GMT
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Original-From:
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Laurentino Martins <LAU@MAILstopspam.TELEPAC.PT>
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Viewed:
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982 times
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At 21:47 27-07-1999 Tuesday , Jon Shemitz wrote:
> Laurentino Martins wrote:
>
> > Also important in all this is the distance the tracks are apart. The • further apart the less friction they have, since the radius is larger.
> > Same happens with wheels.
>
> Why is this? The further apart they are, the greater r*cos(theta) is
> going to be for any given theta. Seems like that would make for more
> turning resistance, not less.
I'll try to explain this with an ASCII picture, but I'm make no promises about the quality... Please use a fixed font (as you always should in newsgroups)
Legend:
#### - Lower part of the track (the part that touches the ground).
OOOO - Inner circumference of turning, if turning on it's own radius.
1 - Here's a bot with a small distance between tracks:
OOOOOOO
#### OOOOOO OOOOOO ####
#### OOOO OOOO ####
#### OOO OOO ####
#### OO OO ####
#### OO OO ####
#### OO small distance OO ####
#### OO <----------------------> OO ####
#### OO OO ####
#### OO OO ####
#### OO OO ####
#### OOO OOO ####
#### OOOO OOOO ####
####| |OOOOO OOOOO ####
|<---->| OOOOOOO
Distance A
2 - And here's a bot with a very large distance between tracks:
OO
#### OOO
#### OO
#### OO
#### OO
#### OO
#### OO very large distance
#### OO <--------------------------------------------->
#### OO (this side not pictured)
#### OO
#### OO
#### OO
#### OO
####| |OOO
|<>|
Distance B
As you (I hope you) can see, the smaller distance between tracks makes the distance A (in the first picture) much larger than the distance B (in the second picture).
Those distances represent how much a track must be dragged sideways for the vehicle to rotate on it's own axis.
The larger the distance between the tracks, the less the tracks are dragged.
In the same way, the smaller the area of the track that touches the ground, the better.
Tracks are a real drag...
Laurentino Martins
[ mailto:lau@mail.telepac.pt ]
[ http://www.terravista.pt/Enseada/2808/ ]
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message has 1 Reply:
Message is in Reply To:
 | | Re: Mechanical question
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| (...) Add on: Also important in all this is the distance the tracks are apart. The further apart the less friction they have, since the radius is larger. Same happens with wheels. Laurentino Martins [ mailto:lau@mail.telepac.pt ] [ (URL) ] -- Did (...) (25 years ago, 26-Jul-99, to lugnet.robotics)
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