[Stuart A, Jeff B, Jeff G, Jim P, Dave, B, Filiberto C,]

In this entry I aim to capture the status of the triple test stand as it was left, following my week at LHO.

After the initial set-up of the triple test stand (see previous aLOG entry 2639) alignment of the BOSEMs could now be carried out on the M1 stage of PR3 (HLTS), using the real-time medm screen meters. Note that the medm screens are available on the triple test stand under the alias of "sitemap2".

Once aligned, the complete suspension was covered with a canopy to isolate it from the turbulent air flow in the staging building assembly room. It should be noted however, that even after being left for over an hour to settle, during the day watchdogs were still being tripped, M1 OSEM position watchdog occasionally, and OSEM AC watchdog continually. To proceed with testing (actuation and sign checks etc) it was necessary to increase the OSEM AC watchdog from 8000 to 16000 counts. 

In preparation for running transfer functions, the following steps were taken:-

- Configured coil output filters in medm screens (taking note of signs T1200015-v1).
- Generating necessary SUS svn infrastructure for testing scripts, templates, data and results directories for SAGM1, SAGM2, and SAGM3 etc.  

However, while running actuator and sign checks a number of issues were uncovered, such as the default visual representation of the "drivealign" matrices not agreeing with the active functional blocks, resulting with unintentional cross-couplings between dofs. This and other issues resulted in the model being reverted to the last functional LLO version from 5th Jan 2012 (svn up -r 1709), since this is what is believed to be in actually in operation on the LLO triple test stand. All supporting common models were reverted too, compiling and installing went smoothly. n.b. both variants of the model have been compiled on the LHO triple test stand, x1sushxts27 and x1sushxts05 - with the later just needing to be installed when required. 

The largest obstacle encountered by far was the inability to actuate. The user model and IOP models both indicated that coils should be actuating, but no drive signals actually reached the coils. In-line break-out tests were conducted chasing signals from the AI chassis coil outputs to the coil drivers, where the drive signal was being prevented from passing through by the BIO. Configuring the BIO correctly proved problematic and so they were ultimately circumvented (for now) by feeding the coil driver signals directly through the "Test" inputs of the coil drivers chassis.

This enabled testing to proceed:-

- Successfully setting coil output filter offsets (actuating) and checking sensor sign was consistent.
- The required M1 DQ channels were added do the x1sushxts27.ini file, to enable DQ channels for DTT transfer functions to be taken.
- DTT TF templates were updated for X1 sensor and X1 excitation channels.

During working hours it was impractical to try to obtain a full set of M1-M1 TFs. However, post 18:00 (Pacific) environmental noise had dropped sufficiently to allow the first complete set of TFs to be taken. These M1-M1 TFs for the un-damped PR3 suspension can be found below (2012_04_20_1730_X1SUSPR3_M1_ALL_TFs.pdf).

Following the first set of successful TF functions, damping loops were closed, and another set of TFs taken (2012_04_20_1830_X1SUSPR3_M1_ALL_TFs.pdf).

The PR3 TFs obtained look mechanically sound and in good agreement with the model. There is however some excess environmental noise coupling in from 5 Hz and above for some dofs. 

To wrap-up the first set of results for this suspension (and test stand), the data, scripts and plots have all been committed to the SUS svn.
Also, a BURT snapshot has been taken of this functional triple test stand configuration called "20120420_x1sushxts27_PR3" which has been saved at /opt/rtcds3/tst/x1/cds_user_apps/trunk/sus/x1/burtfiles. To avoid any confusion, all other BURT snapshots were deleted, with the changes being committed to the SUS svn.

Finally, I wish to thank the efforts of all those involved at LHO (LLO and elsewhere) in getting this test stand up and running!

Pic 2012-04-19-499 shows the iMac interface to the test stand and PR3 under test (under canopy).
Pic 2012-04-20-509 shows the test stand electronics rack in the staging building lobby.