Guiding Control Subsystem (GCS) Overview 10-04-2006
Dec 13, 2015
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
GCSGCSsubsystemsubsystem
AGw control AGw control computercomputer
AGw AGw hardwarehardware
AzCam serverAzCam serverWindows XPWindows XP
AzCam serverAzCam serverWindows XPWindows XP
Guide Guide CamCam
WFS WFS CamCam
.... for each AGw unit
PCSPCS
PSFPSF
PEPSI support
PEPSI needs access to the images of the guide cam
GCSGCSsubsystemsubsystem
PEPSI control PEPSI control computercomputer
PEPSI PEPSI hardwarehardware
AzCam serverAzCam serverWindows XPWindows XP
Guide Guide CamCam
PCSPCS
PSFPSF
IIFIIF
IIF is used to request guide cam image
GuidePic PEPSI PEPSI
InstrumentInstrumentRequest
Pic
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