Subject:
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Re: **lego motors?**
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 12 Apr 1999 14:54:37 GMT
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Original-From:
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S. Crawshaw <sc10003@eng.cam=IHateSpam=.ac.uk>
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Viewed:
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944 times
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On Mon, 12 Apr 1999 BMajik5127@aol.com wrote:
> Hi I built a robot and it wont travel straight at equal power levels? Why
> do I need to set the motors at such different levels to get the bot to travel
> straight?
Quite simply, no two motors run at exactly the same speed for a given
power level. (Slight differences in the wheels, or flexibility in the
axles will also produce the same effect, although probably much less
noticeable) There's no simple answer, but here are three ideas:
If you're really bothered about going straight, you'll have to use one or
more sensors to actually _measure_ the direction of travel (maybe rotation
sensors on the motor outputs to ensure they run at the same speed)
If you can accept a small amount of inaccuracy, then a "car"-type robot
(one motor powering the rear wheels and steering on the front wheels) will
run pretty straight - but you still need to be sure that the steering is
central.
A more technically involved idea, which I've never heard tried: attach the
two wheels to each other through a gearbox, so that by changing gear you
change the ratio of their speeds. Has anyone ever tried something like
this?
Stuart
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message has 3 Replies:
 | | Re: **lego motors?**
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| Hmmm, Lego gearboxes. I've just spent two weeks playing with different styles off gearbox. I haven't found a good powered solution yet. The problem being that the standard gears just don't mesh nicely enough. Making a gearbox is simple enough and (...) (25 years ago, 12-Apr-99, to lugnet.robotics)
| | | Re: **lego motors?**
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| I've been thinking in building an automatic gearbox with two speeds. If the motor was making too much strength it would lower the gear, and if it's running too fast it would increase the gear. Is there any design like that already built? Maybe with (...) (25 years ago, 12-Apr-99, to lugnet.robotics)
| | | Re: **lego motors?**
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| From: S. Crawshaw <sc10003@eng.cam.ac.uk> (...) (URL) has a few robots which use an adder/subtractor to do this, and there are links to all of the other similar designs on the internet that I am aware of. alex -- Did you check the web site first?: (...) (25 years ago, 12-Apr-99, to lugnet.robotics)
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Message is in Reply To:
| | **lego motors?**
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| Hi I built a robot and it wont travel straight at equal power levels? Why do I need to set the motors at such different levels to get the bot to travel straight? I am using the click and drag software that came with the rcx. any help much (...) (25 years ago, 12-Apr-99, to lugnet.robotics)
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