Subject:
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Re: Mindstorm/CyberMaster Swap
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 15 Dec 1998 16:31:48 GMT
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Viewed:
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1805 times
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> > > The third motor output (and only this one) has the the ability to • report
> > > motor current (in mA approx) which makes it possible to do stall • detection.
> >
> > You can do stall detection this way? How can this be done using NQC,
> > say?
> >
> > I've brought up this issue in this discussion group earlier, but noone
> > knew how to do stall detection, or so it seemed to me.
>
> Any of you have confirmed this?
> Some time ago in a few test I've made the only I could read with
MotorCurrent() was if the motor was running...(?)
Okay, I've just made some measurements on the motor current when driving the
grabber tool on the CyberTruck model from the CM set. When off the current
is (naturally) zero. When closing and lifting the current varies between
20-60mA. When stalled at the end of its travel the current varies between
80-110mA. Hence the following is a suitable few methods to raise and lower
the grabs in Bot-Kit.
------------
CyberTruck>>motorStallCurrent
"Answer the average motor stall current"
^95
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CyberTruck>>raiseGrabs
"Raise the grabs. Stop when the motor stalls at the end of travel"
toolMotor forward start.
self waitUntil: (toolMotor motorCurrent >= self motorStallCurrent).
toolMotor stop.
------------
CyberTruck>>lowerGrabs
"Lower the grabs. Stop when the motor stalls at the end of travel"
toolMotor backward start.
self waitUntil: (toolMotor motorCurrent >= self motorStallCurrent).
toolMotor stop.
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Seems to work fine providing you don't expect the motor current to be
particularly stable and accurate but just report the approximate state of
the motor. Sorry, I don't know how to do it in NQC, but I imagine that it is
possible. Anyway, the above test proves that stall detection does work.
Best regards,
Andy Bower
http://www.object-arts.com/Bower/Bot-Kit
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Message is in Reply To:
 | | Re: Mindstorm/CyberMaster Swap
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| (...) Any of you have confirmed this? Some time ago in a few test I've made the only I could read with MotorCurrent() was if the motor was running...(?) Laurentino Martins [lau@mail.telepac.pt] [(URL) (26 years ago, 15-Dec-98, to lugnet.robotics)
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