Subject:
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Re: Newbie needs Help
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 6 Jun 2006 19:16:25 GMT
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Viewed:
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3480 times
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In lugnet.robotics, Rajinder Dhillon wrote:
> > So, you're best option would be to increase the speed.
>
> > Finally, remember, you can mechanically connect all the motors together, so
> > they are driving the same wheels. This assures all wheels are getting the
> > maximum amount of power.
>
> Steve,
>
> Philo's page on 'Wheels, Tyres & Traction' seems to imply that increased
> speed will not make much of a difference or am I reading that wrong?
>
> By 'mechanically connect' do you mean by using two differentials?
>
> The maximum 'safe' gearing down ratio was a general question. I was hoping
> for an answer like 'anything below 100:1 is fine'.
>
> Raj
One rotation sensor and a differential will allow you to compare the rotation of
two wheels. If the driven wheel and the undriven wheel come in the two sides of
the differential, and the rotation sensor is connected to the drive ring, then
the rotation sensor will only rotate if the wheels are going different speeds.
In theory, you should be able to tell forward slip from the backward slip of
being pulled by the other bot. In theory. I haven't tried it.
Note that on farm tractors the drawbar height is lower than the height of the
rear axle, so that the pull of the tool creates less lifting torque on the front
end. Also, note that the net torque is *always* trying to lift the front end,
even with the drawbar below the axle. The rotation point of the torque is the
tire/ground contact point, *not* the axle. The lifting torque on the front end
will be proportional to the distance between the drawbar and the ground, *not*
the distance between the drawbar and the axle. You want to maximize the weight
to the front. In farm tractors, there is a a bracket on the front end that
allows you to add weights.
-dave
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Message has 1 Reply:
 | | Re: Newbie needs Help (diff sensor)
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| Some varied thoughts here: (...) I might be wrong, but my understanding of the Lego differential gearing is that if both shafts are turning at the same rate and direction, the outer gear/shell will turn at the same rate as the axles. Only when the (...) (18 years ago, 6-Jun-06, to lugnet.robotics)
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Message is in Reply To:
| | Re: Newbie needs Help
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| (...) Steve, Philo's page on 'Wheels, Tyres & Traction' seems to imply that increased speed will not make much of a difference or am I reading that wrong? By 'mechanically connect' do you mean by using two differentials? The maximum 'safe' gearing (...) (18 years ago, 6-Jun-06, to lugnet.robotics)
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