The monolithic payload has been suspended for the second time without any particular problem. A rough balancing and a very preliminary positioning have been performed too.
Yesterday a second iteration devoted to the fine payload balancing and positioning have been performed. At the marionette level a small mass (about 20 g) attached on the wing in East side direction (Theta Z d.o.f.) has been removed while a mass of about 40 g has
been attached on the South side wing balancing Theta X d.o.f..
This morning after a quick check on payload positioning and behavior, the mirror eating process started with the goal to close the tower for its evacuation.
The new one are normally opened (i.e. the same type of all the other motors installed on those towers).
The logic control card inside the WI motors crate has been upgraded in order to manage the standard condition (normally opened - NO) for all end-stroke switches.
So, all 24 slots accept motors with NO end-stroke switches.
Also the vme motors board has been upgraded accordingly.
At WE where there were some unused slots the motor has been moved to the first free slot and the configuration file has been updated.
As soon as possible we'll do the same for NE.
At WE and NE we kept the possibility to connect to slot 24 one motor equipped with NC end-stroke switches.
After a brief investigation, we found that the origin was instead an inversion of one motor phase, whose effects were however equivalent to an inversion of the end-stroke switches.
Consequently, we corrected the motor phase by acting on the air side motor connector (the one plugged to the motor crate).
Afterward, during the final test, we noted some problem in the "backward" end-stroke, in particular it was remaining close (normal state is open) also when the motor was moved in the "forward" direction. This might be some failure at level of the "backward" end-stroke switch, that prevents to move the motor in "backward" direction.
On Monday 22nd, in order to temporarily overcome this problem and move the motor (needed for the fine balancing/orientation of the marionette), the end-switch has been disconnected at level of the motor crate connector.
A fine balancing of the Marionette has been performed to improve its orientation around ThetaX and ThetaZ degrees of freedom. A small mass (16 g) has been added on the Marionette wing on East side.
A manual orientation, by using the mobile junction box, has been done in accordance with the Local Control optical lever arms needs. Minor adjustments will be done in the next days by acting on the setting up accommodated within the oven.
After all these activities, the Inverted Pendulum has been centered by acting on the Helmholtz coils and then the Inertial Damping loops have been successfully closed for a few minutes.
Finally, the protective film (first contact film) has been removed on both sides of the Mirror (H. Vocca)
Also the vacuum side cabling has been installed.
Two masses of about 200 g each one have been screwed on the Reference Mass top, while two small masses of about 72 g each one have been attached to the metallic ears of the Reference Mass.
The payload weight adjustment, adding small masses and moving the fishing roads, has been performed too. A fine balancing of the marionette together with the fine payload orientation will be done next week.
The payload has been first blocked on its safety structure within the tower and then the ears have been dismounted. This has been done to better match the new payload weight with the old one (with metallic suspension wires).
The machining will be done reducing the ears weight of about 1.2 kg.
Next days the fine alignment of the mirror will be performed in accordance with the Local Control needs.
The metallic frame and the payload have been protected with transparent plastic film and left in the cleaning area under the NI tower.
Going back trhough the data, we see about the same situation. Probably we have been always close to the saturation.
Probably this noise is generated by the turbo pump. We can look at the same sensors at PR tower, and compare the noise before and after the isolation of the pump by a bellow: the difference is huge. It would be really nice to install the next bellow at NI turbo pump.
In fig 1 the probe 'aux' is acc2. It was not present before today. I didn't realize soon the problem because I was convinced that the critical level for the reconstructed signals was close to 10000.
The signal is quite large around 150 Hz, and it is not like that in other suspensions (fig 2).
zCorr xCorr txCmir tyCmir
0 -9.9 0 -9.9 DAC2_5
0 10.1 0 -10.1 DAC2_6
10.25 10.25 -10 0 DAC2_7
-9.75 -9.75 -10 0 DAC2_8
It is surprising that the introduced umbalancing are exacly the same as before.
In figure the behavior of xDamping is shown: the 0.6 Hz resonance is damped in the usual time scale.
The global calibration of the driving has been roughly checked. It seems good within 10 %.
I didn‘t check the behavior of the dampers in case of very large oscillation (I didn‘t want to detach the magnets the first day). It is clear that we could have less efficiency, or even bigger problems, due to the reduction of the available force (a factor of 2).
The interpretation of the accuracy in angle control III row of the plot set al the level of the marionette is more tricky because a detailed monitor of the locking/AAalignment operations should be performed.
Also, as usual, we note the tracerous behaviour of NI accelerometers. I have just asked Paolo about the bump in NI-F0Accel signals probably affected by aliasing (TBC).
The behaviour of the control loops is the same as before, but this setup should allow to use a global signal for the position control of the suspension along z, instead of the LVDT signal.
The LVDT and ACC signals available in the DAQ have the same names as before, but the degrees of freedom monitored are changed: now the names are coherent with the usual conventions.
I found the ID and LC loops opened as reported on the entry n. 11210, so that I performed the actions as follows:
- at about 17:50 local time I stopped and re-started the Slow Monitoring Server as well as the DSP Server. By using the standard software card (dampNI.hrc, v6r0) I tried to close the ID loops through SuperVisor client but I did not succeed;
- I tried to close the ID loops by using a previous version of the software card (dampNI.hrc, v5r3), but even with this card it has not been possible to close the inertial damping loops (correction signals very small);
- at about 18:35 I stopped again the Slow Monitoring Server and the DSP Server;
- at about 18:40 I rebooted the rio48a and restarted the complete sequnce from scratch (start GxServer, start DSPServer and start SMServer). After these actions I closed again the ID loops by using the SuperVisor client (software card dampNI.hrc, v6r0) but I did not succeed. I suspect a failure on DAC card (to be checked).
In the attached plot the respose of the LVDT sensors (diagonalized signals) together with the accelerometer sensors (diagonalized signals and non diagonalized signals) with the ID loops opened, are reported.
 | Following the unlock during the locking process this morning (807612907), the NI mirror was oscillating at 300mHz. The relevant damper was switched on and this calmed the suspension. However, it was necessary to switch it off manually, rather than leaving it to do so by itself, as it was causing a high frequency oscillation, particularly visible on the tx degree of freedom, as can be seen in the attached plots. |
of the WI and NI suspension towers.
Attached file: Jul_30_xzIP.gif
