Subject:
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Re: Mindstorms Novice
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 8 Feb 1999 02:02:11 GMT
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Viewed:
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1423 times
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Thomas Main wrote:
> ...
>
> Walker:
>
> I built a walker based on the leg design #7 on page 27 of the
> Constructopedia. Unfortunately, everytime i tried to run this bot, my
> motors would get so out of sync that it would barely move and instead
> just sort of swayed from side to side. Are everyone's motors this
> out-of sync? I rebuilt the model using only one motor to power both
> wheels and it worked fine - except I can't steer with only one motor.
> Any thoughts about the motor speed difference or work-around solutions
> would be appreciated.
Ah-ha! This looks like a job for... (insert fanfare here) Leo's infamous
"adder/subtractor", tentatively being called the "differtrans". Of course,
you'll need another differential unit -- the RIS only comes with one. Spare
parts set 5229 has a differential and several gears, and is probably the
easiest way to get an additional one.
For details on the adder/subtractor, check out the following URL's:
(pilfered shamelessly from another message on this newsgroup)
http://carol.wins.uva.nl/~leo/lego/diff.html
http://www.phred.org/~alex/lego/wanderer.html
http://www.geocities.com/SouthBeach/Surf/6112/
http://www.steamboat-software.com/~dhm/
http://www.jumpgate.com/
http://members.xoom.com/legorobotica/project4/camcart_en.html
http://www.phred.org/~alex/lego/plat.html
http://www.phred.org/~alex/lego/dadsdesign.html
I would highly recommend actually building one to see how it works... its
operation is not that obvious from many of the pictures and drawings that I
have seen. Although many refer to a special 1x1 technic brick with a hole,
or a 2x1 brick with 2 holes, it is not, in fact, necessary to use such
unusual pieces to build one. My simplest (and tiniest) implementation
doesn't use any such pieces. I'll try to describe it verbally: I had the
differentials mounted parallel to eachother so that their centers are 4 studs
apart. I used four 8-tooth gears, placing one on each of the axles coming
out of the differentials. On one side of the unit, I used one 24-tooth gear
directly between the 8-tooth gears, and on the other side of the unit, I used
two 16-tooth gears between the 8-tooth gears, each mounted diagonally 1
brick-height above and 1 stud sideways offset from the 8-tooth gears. If
anybody's curious, I have an ldraw file that illustrates this, but if one is
already familiar with the device, I would imagine that the concept is simple
enough to grasp from a verbal description. (also I'm sorta new to ldraw, and
I would imagine that the way I've chosen to do things in it probably bites).
> > Mark
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Message has 1 Reply:
 | | Re: Mindstorms Novice
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| Mark, Thanks for the tips and links. I'll build an add/sub this week and try out another walker. -- Thomas Main main@appstate.edu (...) (26 years ago, 8-Feb-99, to lugnet.robotics)
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Message is in Reply To:
| | Re: Mindstorms Novice
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| It was suggested to me that posing my questions on the newsgroup might be better than using e-mail. So here it goes :) So far, I have tried the first two pathfinder challenges - the "Outback Tracker" and the "Light Tracker." I have also tried to (...) (26 years ago, 8-Feb-99, to lugnet.robotics)
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