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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Sat, 17 Apr 1999 04:14:21 GMT
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Viewed:
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1274 times
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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 coupled to a LEGO rotation sensor that acts as a
comparator. By continuously monitoring the rotation direction and rate of the
comparator, it is possible to dynamically balance (or intentionally unbalance)
the output of the two drive trains. I have used it for a track vehicle and it
works quite nicely. For example, you can place one track on carpet and one on
smooth flooring; after a couple of inches of forward travel, the two sides
balance.
In article <FA31qK.6sw@lugnet.com>, antony@wellic.remove.this.demon.co.uk
says...
>
> 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 1 Reply:
 | | Re: **lego motors?**
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| Could you specify a place where these CAD drawings could be obtained for those who don't frequent newsgroups? Mark Young YoungMM@Hera.WKU.edu -- Did you check the web site first?: (URL) (25 years ago, 19-Apr-99, to lugnet.robotics)
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Message is in Reply To:
| | 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)
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