Subject:
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Re: r/c servos
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 20 Aug 1999 23:29:32 GMT
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Viewed:
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1067 times
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Robert Munafo <munafo@gcctechNO.SPAMcom> wrote:
> In lugnet.robotics, Kekoa Proudfoot writes:
> > Robert Munafo <munafo@gcctechNO.SPAMcom> wrote:
> > > In lugnet.robotics, lego-robotics@crynwr.com (John Barnes) writes:
> > > > [...] This would set the average servo, which needs a pulse from about
> > > > 0.7 - 2.0 mS for 180 degress to one of about 45 steps or every 5 degrees
> > > > [...]
> >
> > I think what John was trying to say was that pulse widths between 0.7 ms
> > and 2.0 ms give servo rotations between 0 and 180 degrees. With 45 steps
> > in that range, you can control the servo in 5 degree increments.
>
> That doesn't make sense either. If a single step of 2.0 ms causes 180 degrees
> of rotation, then how does 45 steps allow you to control it 5 degrees at a
> time?
Let's say a 0.7 ms pulse results in a rotation of 0 degrees.
Let's say a 2.0 ms pulse results in a rotation of 180 degrees.
If all you had were 0.7 ms pulses and 2.0 ms pulses, you'd be able to
choose either 0 degrees or 180 degrees, resulting in a single 180 degree
step (from 0 to 180).
If you could also add a 1.35 ms pulse, and that gave a rotation of 90 degrees,
then you'd have two 90 degree steps, one from 0 to 90, the other from 90 to
180.
If you added 44 pulse widths between 0.7 ms and 2.0 ms, you'd have 46 total
pulse widths separated by 45 steps. Each step would be 4 degrees, for a
total of 180 degrees of motion.
You can divide the 1.3 ms between 0.7 ms and 2.0 ms into as many steps as
you like. As you divvy things up more and more, each step gets smaller.
The step size is 180 degrees divided by the number of steps.
-Kekoa
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Message is in Reply To:
 | | Re: r/c servos
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| (...) That doesn't make sense either. If a single step of 2.0 ms causes 180 degrees of rotation, then how does 45 steps allow you to control it 5 degrees at a time? (...) Are you saying that the servo actually operates in steps of one degree each? (...) (25 years ago, 20-Aug-99, to lugnet.robotics)
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