Subject:
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Re: multiple motors
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Tue, 25 Nov 2003 14:52:40 GMT
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Viewed:
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4116 times
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In lugnet.robotics.rcx, Chris Phillips wrote:
> In lugnet.robotics.rcx, Steve Hassenplug wrote:
> >
> > The key is to use a differential.
> >
> > With six motors (double what I did with three), put two motors on each side
> > (2xRight + 2xLeft), and the other two are connected to a differential, in the
> > middle (like the drive wheels in a car).
>
> I'm just thinking out loud here, but it seems that the problem with the two
> middle motors is that they are wired together.
Yes, that was the problem Brian was having.
And, because the LEGO motors are so efficent, they work really well as
generators. So, if you hook two together, and try to turn 1 and stop the other,
you will have problems.
I'm not sure I explained my suggestion very well. To answer one of Brian's
questions (that I skipped before) I don't think there's a good way to connect
two sets of tripple motors. However, you can easily connect 3 pairs of motors
to the RCX.
Then, you just have to figure out how to hook them up.
It's quite easy to build a diff-drive robot, using two motors to drive each
side, and also steer.
OR, you could build a rack and pinion steering robot, which uses one motor to
steer, and another motor (or two) to drive, through a differential, to the rear
wheels.
So, if you take the steering away from the second robot, so it just has two
drive motors, then add two motors directly to each wheel, now the robot will
have two motors to drive the left wheel (like diff drive), two for the right
wheel (diff drive) and two to drive BOTH wheels (like a normal car)
Each pair of motors is connected together both electrically and mechanically, so
they both drive together.
When you want the robot to turn, you can drive one side forward, the other side
backward, and brake the middle pair. Or, if you want to turn by driving one
side, and braking the other, you can float the middle.
You won't have full power when the robot is turning, but that's not usually as
critical as when you're driving forward/backward.
Have I explained it very well, yet?
Steve
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Message has 1 Reply:
 | | Re: multiple motors
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| (...) Yes, thank you - you explained it very well. The day after posting the question, I realized a differential would solve the problem... but you stated the solution far more clearly than I had thought of it. Now, of course, I'm trying to think (...) (21 years ago, 26-Nov-03, to lugnet.robotics.rcx)
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Message is in Reply To:
| | Re: multiple motors
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| (...) I'm just thinking out loud here, but it seems that the problem with the two middle motors is that they are wired together. So even if the RCX is told to float the motor output, both motors will want to turn together. If one turns, it will act (...) (21 years ago, 25-Nov-03, to lugnet.robotics.rcx)
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