TMS Meeting Minutes, August 6, 2020

Attendees: Andrew, Breann, Heejoo, John, Matthieu, Trenton, Yang (Zoom meeting)

Meeting discussion summary:

  • Heejoo and Trenton working on data analysis for TMS data over elevation change
    • Elevation change with collimation model
    • Elevation change without collimation model
    • Plot of variation in results with different telemetry
    • Consider doing analysis of sensitivity of data to dropped channels (perhaps with a reduced data set)
      • Can we identify sensitivity vs. geometry; are there specific geometries which are most problematic to loss of channel
  • Yang provided updates on software progress and current status
    • Comparison with Ciddor vacuum correction has not yet been completed, but will be soon
    • Mainly concerned with behavior of software and how things work together
    • Past week, focused on developing the necessary compononents and putting them together
    • Suggests scheduling two tests for next week
      • First test: run whole TMS setup with new software (expecting lots of problems) to observe how things behave
      • Second test: test if the system works after corrections applied following the first test
      • WIll provide a summary of current software status with challenges we may face after completing these tests
    • Most of the individual components are ready (but may have some problems)
      • Software for raw measurements, Jacobian calculation, vacuum correction
      • Need to be dropped in to work with John's current script
    • Problems with eTalon software have been resolved
  • Yang's questions
    • Biggest challenge is 32 bit vs. 64 bit in Python 2.X vs. Python 3.X
      • The machine where scripts are run is using Python 2.6, which is old and obsolete
      • Want to move forward to 64 bit and Python 3 (Yang's software is written in 64 bit)
      • Support scripts have been moved to 64 bit machine, but these have not yet been tested
      • Older TMS programs are written in Python 2.6 and won't work in Python 3
        • Must use programs to convert Python 2 to Python 3
        • Yang must manually go over the conversions to correct files
      • Matthieu and Yang to meet tomorrow to discuss this topic further
    • We don't yet have a way to read/write telemetry in Python (working on this); software engineering issues
      • May have a way to read telemetry, but do not have a way to write telemetry (need to write a telemetry library)
      • We have a data dictionary for reading telemetry
    • Telemetry questions
      • PMC primary mirror air temperature is the right one
      • Weather station humidity
      • Post-processing of temperature data will be completed by Heejoo/Trenton
    • Telemetry writeout
      • Yang thinks we should write out two streams throughout the night
        • One stream: dynamic data
        • Second stream: static data
    • Jacobian matrix transformation
      • Code is completed, and Yang believes it is correct, though he has no direct comparison to Stephanie's
      • Stephanie's code includes output data, but it is unclear the conditions under which this data was taken
      • Did two comparisons instead
        • Compared Mathematica output with Python output and they showed good agreement
      • Yang found some difference in calculated pose when bad channels are dropped from the sensitivity matrix
    • Row order doesn't matter, so long as it agrees with the input vector
      • First entry in length vector from Ch. 4, so the first row in sensitivity matrix may come from Ch. 4
    • Output (Rx, Ry, Rz, x, y, z)
      • Want to ensure that interpretation of results is consistent with the old way
      • Old code also outputs the negative of the output vector
      • ml3.py computes the appropriate change (reference - pose)
      • Current output also includes the radius, but this is not currently being used
    • Yang thinks John's script loads an offset from the last line of the offset file
      • The reference position is measured from the offset file (equivalent to a reference pose)
      • We need to have a reference pose and a way to update it once collimated with FPIA
      • From configuration file, can est. a baseline pose, irrespective of any measurement, at the start of the night
      • John's reference position changes multiple times throughout the night as FPIA converges
      • TMS may be used to reduce noise from structural steel changes, and FPIA may be used to correct mirror changes (e.g. front to back thermal gradients)
      • Andrew: start with reference pose, then update to a working reference when FPIA converges, then continue this process throughout the night
      • Using a text file is nice because if you screw something up, it's easy to fix things; also, a text file shows you a history of your reference
    • Current measurement code outputs Sx and Dx measurements (had two sides two years ago), but we currently only have one side
    • Current method of running the software requires lots of knowledge about how the system operates; multiple steps requiring multiple scripts
      • Run FPIA, another script to reset measurements, then start the measurement loop
      • There are detailed instructions for how to operate the system
      • Yang asks if we still want to use this format in the future
      • While testing, we need a human actively involved, but eventually, we would like to develop a little GUI to assist with seamless use
      • How much human interaction is needed is dependent on the potential failure points of the system
    • For next week's tests:
      • Yang will try to make the software as though it is operating just as it was before (from the POV of John's script, it will be operating just the same)
      • First test, imagining lots of issues, where some can be resolved on site, and others will be resolved after the test
        • Would like to manually perturb the primary (John or Heejoo will accomplish this task)
      • Plan for the second test will be tweaked following findings of the first test

Action Items:

  • Heejoo will schedule time with the telescope for Yang's testing
Topic revision: r1 - 07 Aug 2020, TrentonBrendel
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