Subject:
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Re: Adder/Subtractor revisited
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Newsgroups:
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lugnet.robotics
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Date:
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Sun, 31 Jan 1999 21:24:57 GMT
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Original-From:
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Matt Sailors <MEDINFO@AROS.ihatespamNET>
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Viewed:
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827 times
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Reno,
no the purpose of the adder/subtractor is to supply power to two
outputs based on the differential between two inputs. So if you have
two inputs (A, B) and two outputs (X, Y), you get the following
equations for rotational velocity (of course it depends on how you label
the inputs):
X := A + B
Y := A - B
So to move straight ahead, you supply power to just A, therefore X := A
+ 0, Y := A - 0.
To turn you apply positive or negative rotational velocity to B (run the
motor forwards or backward) To turn right assuming X is on the left):
X := A + B
Y := A - B
To turn Left assuming X is on the left):
X := A + (-B) = A - B
Y := A - (-B) = A + B
To turn in place just power B.
This allows a vehicle to track straight without having to compensate for
differences in rotational velocity of the motors powering separate sides
of the vehicle. there are other pages with designs to combine the
power from multiple motors through a differential, Check out Craig
Lampe's Lego R/C car chassis at
http://www.nd.edu/~lego/grp2/www/legocar.htm
Matt
R M Sailors
medinfo@aros.net
Reno Pittner wrote:
>
> I'm a little confused again. The explanation of the
> adder/subtractor was to allow one to power each wheel
> while the differential compensated for the different motor
> tolerances, allowing the bot to travel in a straight line.
>
> Clear as a bell, until I built one. I chose the ones on
> the Cyberia site as it was the most condensed versions. Both
> designs (I think) use a single engine to control forward movement
> while the other controls the steering. I believe Alex's father
> design does the same. If this is the case, it seems to conflict
> with the explanation above.
>
> The motors are geared to the differential gear. Is this correct?
> What happens if you power the axle gears?
>
> Thanks,
> Reno
> --
> Did you check the web site first?: http://www.crynwr.com/lego-robotics
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message is in Reply To:
 | | Adder/Subtractor revisited
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| I'm a little confused again. The explanation of the adder/subtractor was to allow one to power each wheel while the differential compensated for the different motor tolerances, allowing the bot to travel in a straight line. Clear as a bell, until I (...) (25 years ago, 31-Jan-99, to lugnet.robotics)
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