Skip to content

Commit

Permalink
Completed a version with status of technotes as of June 4th
Browse files Browse the repository at this point in the history
  • Loading branch information
@nsevilla
nsevilla committed Jun 6, 2024
1 parent aaf61c5 commit 2860973
Showing 1 changed file with 31 additions and 27 deletions.
58 changes: 31 additions & 27 deletions index.rst
View file
Original file line number Diff line number Diff line change
Expand Up @@ -8,12 +8,15 @@ Summary of M1M3 Tests
**This technote is a work-in-progress.**

.. abstract::
This technote summarizes the M1M3 dynamic tests in the context of glass safety. It will be periodically updated with new results. The current technote corresponds to status as of June 4th 2024.
This technote summarizes the M1M3 dynamic tests and corresponding technotes in the context of glass safety as of June 4th 2024.


Introduction
============

This technote summarizes the M1M3 dynamic tests in the context of Glass Safety. It will be periodically updated with new results. The current technote corresponds to status as of June 4th 2024. A list of technotes with their updated dates and associated data sets is provided below. Following that, the list is broken down into thematic sections on different aspects of M1M3 Glass Safety and a summary of current results and next steps is provided.


Related tickets
===============
This technote is linked with:
Expand Down Expand Up @@ -92,65 +95,65 @@ Index of tests and verification
Force balance tests
-------------------

* `SITCOMTN-079 <https://sitcomtn-079.lsst.io/v/SITCOM-1111/index.html>`_ M1M3 Iterative Improvement of LUT Through Balance Forces
* `SITCOMTN-079 <https://sitcomtn-079.lsst.io/v/SITCOM-1111/index.html>`_ **M1M3 Iterative Improvement of LUT Through Balance Forces**

*Results*: After the improvements made in July 2023 to the Look-Up Table (LUT), the hardpoint measured forces have been minimized. The “rule of thumb” for the LUT is that we should expect about 1/1000 correction. Our mirror weighs 170,000 N. We should expect to get within 170N. It looks like we are within this range.

*Pending tasks*: To further improve the LUT, tests could be performed to validate that we have reached convergence and the LUT includes all the gravitational loads dependency. Merge latest version of technote into main.
*Pending tasks*: To further improve the LUT, tests could be performed to validate that we have reached convergence and the LUT includes all the gravitational loads dependency. Merge latest version of technote into main, technote format is old.

* `SITCOMTN-092 <https://sitcomtn-092.lsst.io/v/SITCOM-1081/index.html>`_ M1M3 Force Balance System - Inertia Compensation
* `SITCOMTN-092 <https://sitcomtn-092.lsst.io/v/SITCOM-1081/index.html>`_ **M1M3 Force Balance System - Inertia Compensation**

*Results*: After applying different forces at 10% to 100% performance, maximum are occasionally seen at above 1000N, whereas the limit currently stands at 900 N.

*Pending tasks*: Update technote to reflect most recent results (shown at the Glass Safety review) and merge into main. Define next steps, and possible risk minimization.
*Pending tasks*: Update technote to reflect most recent results (shown at the Glass Safety review) and merge into main. Define next steps, and possible risk minimization. Technote format is old.

* `SITCOMTN-107 <https://sitcomtn-107.lsst.io/>`_ M1M3 Actuator Delays and Following Errors
* `SITCOMTN-107 <https://sitcomtn-107.lsst.io/>`_ **M1M3 Actuator Delays and Following Errors**

*Results*:
*Results*: For aggressive slews, the measured forces do not track the applied forces well at all. So it appears that the problem with large hardpoint forces for the aggressive slews is more serious than just time delays.

*Pending tasks*:
*Pending tasks*: We need to understand why the measured forces are deviating so strongly from the intended forces.

Bump tests
----------
* `SITCOMTN-083 <https://sitcomtn-083.lsst.io/>`_ M1M3 Mirror Cell Bump Testing
* `SITCOMTN-083 <https://sitcomtn-083.lsst.io/>`_ **M1M3 Mirror Cell Bump Testing**

*Results*:
*Results*: Tests have been performed throughout several days. Map of failures per actuator created, together with typical failure modes (mostly on Z axis), for ~200 N bump tests. These failures modes are mostly over/undershoots of applied force vs demand. No actuators came to fault.

*Pending tasks*:
*Pending tasks*: Make full (1+ years) history of bump tests to drill down into a frequentist probability of failure modes. Determine course of action with current numbers, what is the requirement other than 'not fault?'.

Hardpoint tests
---------------
* `SITCOMTN-081 <https://sitcomtn-081.lsst.io/>`_ M1M3 Hardpoint Oscillations During Elevation Slews
* `SITCOMTN-081 <https://sitcomtn-081.lsst.io/>`_ **M1M3 Hardpoint Oscillations During Elevation Slews**

*Results*:
*Results*: Evidence shown for oscillatory behavior during elevation and azimuth slews, by measuring hardpoint forces and identifying events above a 100 N threshold. Analysis of a one-off event started by TMA in June 2023 demonstrated no apparent coupling to M1M3.

*Pending tasks*:
*Pending tasks*: Technote marked as current needs a review or update. Pending a more systematic analysis of slew events and identification of low amplitude oscillations at low elevation/earthquake behavior.

* `SITCOMTN-082 <https://sitcomtn-082.lsst.io/>`_ M1M3 Hardpoint Breakaway
* `SITCOMTN-082 <https://sitcomtn-082.lsst.io/>`_ **M1M3 Hardpoint Breakaway**

*Results*:
*Results*: Breakaway system works in general with notable exceptions that need to be investigated: HP2, HP5 breakaway system faults at low (<30 deg) elevations, response shape also different.

*Pending tasks*:
*Pending tasks*: Technote format is old and seems missing some discussion, conclusions.

Stability tests
---------------
* `SITCOMTN-084 <https://sitcomtn-084.lsst.io/>`_ M1M3 Position Repeatability Analysis
* `SITCOMTN-084 <https://sitcomtn-084.lsst.io/>`_ **M1M3 Position Repeatability Analysis**

*Results*:
*Results*: The initial specifications on the mirror positions and rotations are not met, especially for the piston (z displacement). After discussion with experts, it was realized that these displacements are normal and correspond to the sag of the mirror cell due to gravity change that should be compensated by adjusting the M2 and camera hexapods. However this procedure does not seem to counteract the effect at the required level. For az only movements, the mirror displacements are within the specifications but for the rotation around the x axis where there are some outliers. The mirror rotation seems also correlated to the azimuth difference for movement < 50 degrees. For larger TMA movements the mirror rotation is within the specifications. Raise/park repeatability is verified as well.

*Pending tasks*:
*Pending tasks*: Confirmation of the observed behavior with higher statistics. Study how to reduce the scatter for the correction in Z through adjustments of M2 and hexapods.

* `SITCOMTN-095 <https://sitcomtn-095.lsst.io/>`_ M1M3 Settling Time After a Slew
* `SITCOMTN-095 <https://sitcomtn-095.lsst.io/>`_ **M1M3 Settling Time After a Slew**

*Results*:
*Results*: The requirement is failed using a threshold of 5 seconds after slew start due to a failure in the yPosition and yRotation columns predominantly, due to a slow drift of the cell. However, in a large majority of cases settling happens in < 2 s later and just barely misses the requirement for the system. NB that we have included RMS and bias of the IMS value, despite not being strictly the specification, as we considered it relevant to highlight these slow drifts that may not incur in any jittering at all.

*Pending tasks*:
*Pending tasks*: Repeat analysis with updated adjustments to commands (which could be fixing the errors) when mirror is in place.

* `SITCOMTN-109 <https://sitcomtn-109.lsst.io/>`_ M1M3 Analyze position and rotation stability throughout a tracking period
* `SITCOMTN-109 <https://sitcomtn-109.lsst.io/>`_ **M1M3 Analyze position and rotation stability throughout a tracking period**

*Results*:
*Results*: After analyzing all the two-night tracking we have seen that the mirror remains stable. The duration of the tracking is 42 seconds and not 30 seconds as initially indicated.

*Pending tasks*:
*Pending tasks*: Figure out what is going on with the 42 s 'observing' period.

Requirements
------------
Expand All @@ -160,10 +163,11 @@ For all the tests, the requirements are extracted from the following document:
* `LTS-88 <https://ls.st/LTS-88>`_ M1M3 Mirror Support Design Requirements Document


Related documents
Related documents
=================

`M1M3 Mirror Support Design Requirement Document LTS-88 <https://docushare.lsst.org/docushare/dsweb/Get/LTS-88/LTS-88.pdf>`__

`Glass safety review <https://docs.google.com/presentation/d/1HmmzIUt0XszK0XMS1YZtQiYCvdwajhrZ8p3ZdAVSp14/edit#slide=id.p>`__

.. Make in-text citations with: :cite:`bibkey`.
Expand Down

0 comments on commit 2860973

Please sign in to comment.