Jon,
the problem is that the delay between reality and the Z domain of the
encoder is variable, so good tuning will be
something somewhere in fairyland unless you lower the bandwidth of your
drive right down so that the delay jitter
becomes insignificant in respect to the bandwidth of your system.
j.
On Sat, Jun 18, 2011 at 5:46 PM, Jon Elson <[email protected]> wrote:
> Jan de Kruyf wrote:
> > Jon,
> > I see exactly this in yr pictures: (from the faq on their website)
> >
> >
> > 9. How does angular acceleration affect pulses and error?
> >
> > Angular acceleration does not cause missing pulses. But it does cause
> > some lag in position, proportional to acceleration and T^2. (with T=
> > 100, 50, 25, 13 µs at resolution settings D2, D1 = 11, 10, 01, 00,
> > respectively). The internal position follower will have no problem
> > with acceleration as long as the resulting position error stays within
> > 256 increments (4 increments per quadrature period) for resolution
> > 2048 PPR, with the limit being proportional in other resolutions. The
> > position follower will catch up at the end of acceleration.
> > Decreasing the basic resolution will reduce acceleration error, if
> > that is of concern for fast loops or removing the SF jumper as
> > described in section 3 above.
> > -------------------------------
> Yes, I read this and it didn't sound too bad. But, I think the lag is a
> LOT more than 100us, up to several
> milliseconds, or maybe 30 times worse than what they state.
> >
> > so I would give that rubbish a miss. It is good for a position
> > readout, but definitely not for a high speed feedback loop.
> >
> I may experiment some more at different resolutions, and see about that
> jumper setting.
>
> Thanks,
>
> Jon
>
>
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