Subject:
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Re: r/c servos and firmware
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 20 Aug 1999 22:35:02 GMT
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Viewed:
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1302 times
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In lugnet.robotics, Ralph Hempel writes:
> [...] The servo takes a 60Hz (approx) pulse width signal between 1 and
> 2 msec.
> The pulses are fed into a little circuit that generates an analog level
> that is used in a comparator whose other input comes from a pot on the
> output arm of the servo. [...] The 1 msec pulse corresponds to one end
> of the limit of rotation, and the 2 msec pulse is the other end. [...]
Okay! Finally I got it! (-:
It sounds to me like servos can't rotate continuously in the same direction. In
other words, they're good for steering but not for turning the wheels that make
the car go. Is that right?
Anyway, having heard that (plus the paragraphs I deleted about calibration and
software) I would have to say that servos don't sound all that useful. At least
not as useful as I was thinking they would be...
How about using stepper motors instead? These are motors that have internal
gear reduction and extra internal fixed magnets, and take pulses (either
positive or negative). If the pulse width is right, each pulse makes it move a
certain (fixed) number of degrees (the size of the step is the angular spacing
of the armature arms divided by the gearbox reduction ratio). Are there any
9-volt stepper motors that work with pulses of 10 msec, or a multiple of 10
msec?
- Robert Munafo http://www.mrob.com
LEGO: TC+++(8480) SW++ #+ S-- LS++ Hsp M+ A@ LM++ YB64m IC13
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Message has 3 Replies:
 | | RE: r/c servos and firmware
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| (...) There are multiturn servos for winches in RC sailboats, but they are REALLY expensive. (...) Well don't give up too fast. They ARE useful for steering, or lifting, or grabbing because we can set the limits of motion. This makes things like (...) (25 years ago, 20-Aug-99, to lugnet.robotics)
| | | RE: r/c servos and firmware
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| (...) Exactly. See (URL) examples. These servos have a little disc or cross on top with holes at the edges. The servos can turn the disc only 45 degrees in each direction. They are used for moving flaps or rudders on model airplanes. You bend a 90 (...) (25 years ago, 20-Aug-99, to lugnet.robotics)
| | | Re: r/c servos and firmware
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| (...) In (...) make (...) least (...) Hello, New mindstorm user...been lurking for a while. WRT to servo motion -- it is fairly easy to modify standard servos for continuous motion. $ would put this motor about the same cost as lego so not sure of (...) (25 years ago, 21-Aug-99, to lugnet.robotics)
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Message is in Reply To:
| | RE: r/c servos and firmware
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| Ok, Here's my 2 cents on servos...read to the bottom if you are interested in helping to develop the code for this. The servo takes a 60Hz (approx) pulse width signal between 1 and 2 msec The pulses are fed into a little circuit that generates an (...) (25 years ago, 20-Aug-99, to lugnet.robotics)
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