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Old 27-09-2010, 10:51 AM
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gary is offline
Join Date: Apr 2005
Location: Mt. Kuring-Gai
Posts: 5,443
Originally Posted by CraigS View Post
I apologise if this question has been asked previously (this is a huge thread).

When used with ServoCat, (or other equivalent), does the Argo issue continuous/periodic drive 'instructions' to the mount, in order to correct for pointing errors during tracking ?

Hi Craig,

Thanks for the post.

Argo Navis has an in-built feature called TPAS - Telescope Pointing Analysis
System. TPAS can analyze and potentially compensate for a range of common
geometric, gravitational flexure and eccentric bearing errors that occur in mounts.

In the Argo Navis/ServoCAT architecture, Argo Navis performs all the object
offset and tracking rate calculations on behalf of the ServoCAT. The ServoCAT
requests object offset or tracking rate information multiple times per second.
The Argo Navis pointing kernel applies any corrections that exist in a TPAS model.
Tracking is simply the first differential of pointing and so the same corrections
take place during tracking. The nature of these types of errors are that they tend to
vary only slowly whilst a scope tracks. The ServoCAT ensures
that the motors are turning at the tracking rates commanded via the motor's servo
loop. Each servo motor is fitted with an optical encoder on its shaft which feeds
information back to the ServoCAT so that it can ensure the motor has arrived at
a commanded position and is turning at the correct rate.

Argo Navis does not provide for any corrections for phenomena such as
periodic errors in a gear chain, however the ServoCAT has the ability to have
ST-4 corrections sent to it via an autoguider.

Best Regards

Gary Kopff
Managing Director
Wildcard Innovations Pty. Ltd.
20 Kilmory Place, Mount Kuring-Gai
NSW. 2080. Australia
Phone +61-2-9457-9049
Phone +61-2-9457-9593
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