Subject:
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Re: Motor power?
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 18 Feb 1999 00:37:00 GMT
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Viewed:
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994 times
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Thanks to all for responding.
The event that spurred me to ask the question in the first place is that I wanted to
use differential power settings to turn (steer) a tracked robot. Unfortunately, this
appear to have no effect on the robot's ability to turn. I verified that the power
settings were actually being used by pushing the View key.
I am aware of the flywheel. My expectation is that the flywheel would average out
power fluctuations to get the right power setting on the output of the flywheel. The
load imposed by the tracked 'bot on the motor/flywheel would make sure that the
power setting would be observed.
On the other hand, I do have a 75:1 mechanical advantage (24:8 followed by 40:8,
followed by 40:8), so I might not be putting enough of a load on the motors to slow
them down to see the effect of PWM control.
The observation was also made that voltage controls speed and current controls
torque. However, in my case, it appears that the counter-torque of the load is not
enough to slow down the motor/flywheel to be observed.
I'll try reducing the gearing to see if that improves the situation. Thanks again.
Cheers,
danm
"John A. Donaldson" wrote:
> I have a tracked bot and I can notice the difference in speed when I set the
> motors to 1 or 4 or 8.
>
> John A. Donaldson
>
> Dave Baum wrote:
>
> > The firmware does do PWM. One reason you aren't seeing much difference is
> > that the motor has an internal flywheel. When the pulse is "on", the
> > motor revs up to speed, then this speed is maintained by the flywheel
> > during the "off" pulse. If you put a bigger load on the motor (i.e. have
> > it move something heavy), you'll start to notice some difference in the
> > power settings. It still isn't great, but at least there is some
> > difference.
> >
> > Dave
> >
> > In article <36CA1856.CCCDC250@seanet.com>, Dan McCabe <danm@seanet.com> wrote:
> >
> > > When I set the motor power (both in RIS and nqc), I expected the speed
> > > of the motor to be proportional to the power setting (i.e., higher power
> > > setting makes motor turn faster and vice versa). However, what I see is
> > > that the power setting appears to have no impact on motor speed.
> > >
> > > Am I doing something wrong? Or is it just that I can't get there from
> > > here? Any insights would be appreciated. (Yeah, I could do the PWM thing
> > > in RCX code, but I hoped that the firmware did that sort of thing for
> > > you; it would be faster and more efficient in firmware).
> > >
> > > TIA
> > >
> > > Cheers,
> > > danm
> >
> > --
> > reply to: dbaum at enteract dot com
> > --
> > Did you check the web site first?: http://www.crynwr.com/lego-robotics
>
> --
> Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message is in Reply To:
 | | Re: Motor power?
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| I have a tracked bot and I can notice the difference in speed when I set the motors to 1 or 4 or 8. John A. Donaldson (...) (25 years ago, 16-Feb-99, to lugnet.robotics)
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