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AdV-SIN (Pre-commissioning)
bertolini, gherardini, polini, tacca, vardaro - 23:25 Thursday 06 May 2021 (51691) Print this report
Issues on SQB1 Motors 4 and 5

Initial issue:

The SQB1 Motor 4 could rotating only in the downward direction, whereas the Motor 5 was could not rotating in both the directions

Investigation performed the 5th May

  1. After the replacement of the Trinamics board in the Motor Box we tried again to move the motor 4. It was working only in the downward direction. We tried to move the motor 4 with the driver of the motor 3 and it worked perfectly in both the directions, whereas when we tried to move the motor 3 with the motor 4 driver it was moving only in the upward directrion
  2. We tried to move the motor 4 with the motor 5 driver and it was not moving in both the directions
  3. We checked with the digital multimeter the cables of the motor 3 and 4 and we fond that the two motor wires were correctly connected
  4. We tried to disable the end-switches via TMCL configuration script but the two motors continued to behave in the same way
  5. We suspect that also the new Trinamics board could be damaged or that the cabling inside the board could be wrong, thus we swap the motor box in the crate with the motor box of SQB2 that was perfectly working the last week. We found the same issues
  6. We checked also the wires of the motor 5 and we realized that one motor wire was not present both at the level of the rack and at the level of the patch panel

Investigation performed the 6th May

  1. We suspected that the end switches of the motor 4 have some troubles and that the misbehaving of the motor 4 could be explained by them. If yes we have some problem when we try to disable them with the TMCL software
  2. We checked the end switches of the Motor 4 with the multimeter and we realized that the End switch near the motor is open whereas the other one is shortcircuited. This explains why the motor 4 could not move in the upward direction
  3. We tried again the Motor 4 with the driver 4. Now it was not moving in bot direction. 
  4. We tried the motor 4 with the driver 3. It was moving in both the direction. We tried also the motor 3 with the driver 4 and it was not moving in both the direction.
  5. We left the motor 4 in the driver 3. But this time we decided to swap also the end switches cables between motor 3 and motor 4. We noticed that the motor 4 connected to the driver 3 in this configuration moves only downward. 
  6. We prepared one male d-sub connector with the same pinout of the end-switch of the motor 4 leaving all the connection shortcircuited. This means that the driver believe that the motor 4 is never at the end of its motion range. 
  7. We disconnect the end switch cable of the motor 4 from the patch panel and we connected it to the dummy end-switches. In this configuration, the motor 4 was moving in both the direction connected to the driver 3
  8. We riconnect the motor 4 to the driver 4 and we moved also the dummy end-switches. Now it was no moving in both directions. We deduced that the channel 4 of the trinamics board was burned

Concerning the motor 5 we found also that one connection in the d-sub 25 connector of the vacuum flange was not connected. We re-welded it and after that the two wires were correctly found checking with the multimeter at the level of the patch panel. We tried to move the motor 5 but it continues to not move. We had the impression that also the driver 5 was burned

We decided to swap again the trinamics board inside the motor box. 

We tested it again and we found that the motor 4 was moving in both directions connected to driver 4 (dummy end-switches), the motor 3 was moving in both direction connected to the driver 3.

In order to test motor 5 (torque) we closed the local control and we observed the Ty correction signal. It was about 7V. We tried to move it in one direction and the Ty_Corr increased. We tried to move it in the opposite direction and the Ty_Corr signal decreased up to 1.5 V. We were not able to decreased it below this value, but in any case the Motor 5 was working in both directions

We realized also that the bench was not well balanced both in TX (+400) and Tz (+200) and we moved some weight on the bench in order to have the TX and TZ DOF oscillating around their working point, i.e TX = -14 and TZ=+7

 

Conclusions:

All the SQB1 6 motors are working now, the local control of the bench can be closed without problem. Now we can work also to center the top stage of the suspension. We left dummy end-switched connected to the motor 4 cable . The End-Switches disable from TMCL software is not working correctly.

Comments to this report:
macchia, capocasa, vardaro, tacca - 10:06 Saturday 08 May 2021 (51706) Print this report
After some checks, SQB1 bench has been prepared and the microtower pumped in order to make some test on the control system in vacuum during the week end.
bertolini - 23:01 Sunday 09 May 2021 (51713) Print this report

After pumping, the position of F0 and F1 were found to be +4700um and +1800um while the bench ended up around +4200um. I have tried acting on Motor#3 to bring F0 around mid-range but the lower end-stop of the fishing rod was reached with F0 still at ~4400um.
This situation indicates lack of mass on the bench and will be easily fixed when venting the minitower. However, in such a configuration it's not possible to operate the vertical control. Therefore i acted on Motor#4 and lowered the bench to Y~ 0 in order to be able to close all the other loops. During these operations i could verify that both fishing rods now work properly. Here the list of following actions:

  • LC Tx, Tz set-points changed and LC angular loops closed. LC controls are stable and LC-Coil-Total is less than 2V.
  • X,Z orientation changed in the SBE process to match the LC's one. Now Z axis is pointing towards North and X axis is pointing towards West; this configuration holds for all suspensions in the QNR system.
  • performed a new diagonalization of the SBE actuators; the residual coupling between the 3 DoF is again less than 10%. The old one, made before the recent installation of new cables, was not good anymore. The new actuation matrix indicates that the stiffness has increased significantly in X and Z.
  • SBE loops (except for Y which is temporarily disabled) were successfully closed and they are stable. Optimization of the control filters will be done in the coming days.

I have left LC and SBE loops open for the night.

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