Use Case:  Calibrate M6 versus Coudé Sensors

Role(s)/Actor(s):
Primary: User (Operator, Maintenance, VLTI-ISS)
Secondary: Nasmyth Beacon,M6, Coude Beam Switching Device, FSS, FSS Strap, FSS Filter Wheel

Priority: Major

Performance: A couple of minutes (1 to 3 minutes)

Frequency: Asynchronous, typ. once after relocation, or any time for maintenance/test purpose

Package Assignment:  Optical Adjustments.

Preconditions:

• Coude Beam switching device is switched On and ONLINE
• Nasmyth Wheel and Nasmyth Beacon are ONLINE
• M6 is ONLINE
• Azimuth is at zero (or at least known) position
• ROS shutter is open

• Send command CALM6 to calibrate M6 in open loop
• ATCS sets CBSD to appropriate position (FSS or FAS)
• ATCS sets NDF to appropriate value
• ATCS switches ON Nasmyth Beacon
• ATCS centers M6
• ATCS performs Guide Probe to Beacon (acquire beacon) and read X-Y position
• ATCS sets M6 alpha to given value

Exception Course: Command failed
• ATCS performs Guide Probe to Beacon (acquire beacon) and read X-Y position

Exception Course: Command failed
• ATCS sets M6 beta to given value

Exception Course: Command failed
• ATCS performs Guide Probe to Beacon (acquire beacon) and read X-Y position

Exception Course: Command failed
• ATCS computes transfer matrix M6 alpha/beta->coude sensor coordinates for the reference Azimuth position (zero? park?)

Exception Course: Command failed
• ATCS stores transfer matrix in database
• ATCS switches OFF Nasmyth Beacon
• ATCS sends final OK reply

• Send command to calibrate M6 in closed loop
• ATCS sets CBSD to appropriate postion (FSS or FAS)
• ATCS sets NDF to appropriate value
• ATCS sets Nasmyth Beacon Intensity level to appropriate value for M6 calibration
• ATCS switches ON Nasmyth Beacon
• ATCS centers M6
• ATCS performs Guide Probe to Beacon (acquire beacon) and read X-Y position
• ATCS closes STRAP loop
• ATCS moves FSS support by given Delta_X with STRAP  loop closed (i.e. M6 is following)

Exception Course: Command failed
• When on target, ATCS reads M6 alpha/beta positions

Exception Course: Command failed
• ATCS moves FSS support by given Delta_Y with STRAP  loop closed (i.e. M6 is following)

Exception Course: Command failed
• When on target, ATCS reads M6 alpha/beta positions

Exception Course: Command failed
• ATCS computes transfer matrix M6 alpha/beta->coude sensor coordinates for the reference Azimuth position (zero? park?)

Exception Course: Command failed
• ATCS stores transfer matrix in database
• ATCS switches OFF Nasmyth Beacon
• ATCS sends final OK reply

• ATCS returns ERROR reply

Postconditions:

• Transfer matrix is updated
• Devices are where they were
• Entry in Log File has been created (parameters TBD)

Notes:
This use case should foresee (priority=desirable), the possibility that the user enters more than one set of alpha/delta (X-Y) pair. The ATCS computes then a transfer matrix for each set ([0;0],[X,0];[0,Y]), compute the average matrix and assess the linearity.

Although the transfer matrix (stored in DB) is defined for a given reference Azimuth Angle, it shall be possible to run this Use Case at any Azimuth Angle
Last modified: Thu Feb 28 10:50:58 UTC 2002