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 15:29:59 GMT
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Viewed:
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995 times
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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 changing it by hand is OK, but a motor just doesn't know
how to wiggle side to side and back and forward when things fail to mesh
first time. A good sincro-mesh would be nice (anyone?).
My tank has the same problem, turning left all the time. Putting a motor in
to
float off mode, makes it turn slowly back on course.
I'll get some pic's of my gearboxes, up onto my web site soon I hope.
Antony.
S. Crawshaw wrote in message ...
> 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 2 Replies:
 | | Re: **lego motors?**
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| (...) Lego's Super Car (8880) comes with a 4-speed gearbox that uses loosely set cogs to engage an axle to an idler gear (I don't know how else to describe it), which means that one can change gears easily at high rpm and not worry about (...) (25 years ago, 12-Apr-99, to lugnet.robotics)
| | | Re: **lego motors?**
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| Check out my "adaptive transmission" LDRAW CAD drawings posted awhile ago on the cad.dat newsgroup. This design largely solves the "go straight" problem. It uses two independent left/right drive trains, interconnected through a single differential (...) (25 years ago, 17-Apr-99, to lugnet.robotics)
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Message is in Reply To:
| | Re: **lego motors?**
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| (...) 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 (...) (25 years ago, 12-Apr-99, to lugnet.robotics)
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