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.
-------------------------------
so I would give that rubbish a miss. It is good for a position readout, but
definitely not for a high speed feedback loop.
j.
On Sat, Jun 18, 2011 at 5:17 AM, Jon Elson <[email protected]> wrote:
> OK, I think I get it, and it is about what I expected from an encoder
> with interpolation.
> It isn't exactly a velocity lag, it is an ACELLERATION lag! I did
> another plot at
> expanded time resolution, http://pico-systems.com/images/vel.png
> and it looks like there is a real lag in responding to changes in velocity.
>
> Does anybody agree that is what I'm seeing here?
>
> Thanks,
>
> Jon
>
>
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