Transcript GCS_Overview_2006-10-04.ppt

Guiding Control Subsystem
(GCS)
Overview
10-04-2006
Tasks
Provide information to the PCS to identify tracking
errors
Provide information to PSF to compensate for
basic wavefront distortions (active optics).
Provide an interface for TCS and humans to
select a proper guide star
Activities
Control AutoGuider and Wavefront sensing
(AGw)units (MODS, AIP & PEPSI AGw)
Control AzCam guiding and WFS cameras
Acquire and analyze camera images
calculate centroid of GS and Zernike polynomial
coefficients describing the Wavefront
frequently send results to PSF and PCS
subsystem
GUI
provide different views for engineers and
astronomers
designed mainly for the needs of astronomers
and telescope operators
graphically keep track of the centroids and WF
development over time
major redesign of the GUI coming soon
Communication
PCS
AGw control
computer
AGw
hardware
GCS
subsystem
AzCam server
Guide
Cam
Windows XP
AzCam server
Windows XP
WFS
Cam
PSF
..
..
for each AGw unit
PEPSI support
PEPSI needs access to the images of the guide
cam
Guide
Pic
PCS
IIF
PEPSI
Instrument
Request
Pic
GCS
subsystem
PEPSI control
computer
PEPSI
hardware
AzCam server
Guide
Cam
Windows XP
PSF
IIF is used to request guide cam image
Guiding Details
Two algorithms available to determine centroid
Default is Gaussian Fit: very precise, not good
with irregularly shaped objects or bad SNR
Optionally, instrument or astronomer can select
Center-of-Weight (CoW) algorithm
CoW is very stable, disregards shape of object
and works with very bad SNR
WFS Details
algorithm just left prototype status and proved
reliability under simulated conditions
uses centroiding algorithm
how to initialize the matrices with the necessary
values is currently discussed with AIP AGw team
details of implementation yet to be discussed, i.e.
derotation, calibration with primary mirror, etc.
TCS interface
currently only a very basic interface is
implemented
start / stop guiding and WFS, status data
needs improvement in cooperation with TCS
developers
Improvements
Foreseeable is the need for guiding on moving
objects
issue has been raised with the AGw teams as
neither OSU nor AIP have a solution for this yet
agreed on first do guiding on static objects
after that they want to check how their hardware
can support the GCS with moving objects