1. Weekly meeting Cascina 9 Jan 2007
MSC recent activities
Weekly meeting
Cascina 9 Jan 2007

2. MSC activities during last month have been focused on
12/6/2018
MSC activities during last month have been focused on
Test of new strategies to face the winter (seism,mseism)
tests of improved vertical control
Improved DSP card logic to use “hybrid” filters (seism-mseism)
Development and implementation of new operation interface
Development of automated suspension re-centring
EM-MSC
wwwwwww

3. Winter issues: STD scheme and blending used until Dec 2006
ACC
LVDT + HP LP
cross IP
fcrossover = 50 mHz
Compromise between:
30 mHz (wind disturbance through ACC)
and
70 mHz (mseism disturbance through LVDT)
Note: since 2005 we have much larger margin on
number of digital filter coefficients in the DSP and speed.
EM-MSC

4. Winter issues: hybrid filters (W2S tuning with no download)
mix =1 (mseism) :
similar to 40 mHz + notch improvement + improvement above 50 mHz
ACC
LVDT +
HPm
LPm IP
HPw
LPw
mix
cross
mix =0.5 :
similar to the 50 mHz + notch improvement
mix =0 (wind):
featured to 50 mHz + notch improvement + improvement below 50 mHz
effect of HPLP featuring
EM-MSC

5. Experience overview (from STD + to anti mseism)
mix = 0.5 (close to old STD ID) to mix =1 (sea)
majorana - 15:17, Thursday 04 January 2007
EM-MSC

6. Experience overview (Dec 4th - Jan 4th)
mix = 1 versus STD 50 mHz
similar mseism (sea) conditions
Overall reduction of mseism re-injection
Overall improvement shown on zCorr (i.e. smaller longitudinal motion of the mirrors)
EM-MSC

7. Other tests: this week…
Comparison between an improved anti-wind (G.Losurdo and the running one), it will be tested.
Target: release a hybrid configuration for the run
EM-MSC

8. (Paolo Giovanni Ettore) Development of flexible design and operation
Many parallel efforts
GIPC
(Paolo Giovanni Ettore)
Development of flexible
design and operation
(Paolo Giovanni Ettore)
Filter re-design
(Matt)
No path has been abandoned !
EM-MSC

9. mseism VS tilt
EM-MSC

10. cavities locked independently
mseism ( ) mHz:
relevant LVDTs seismic component in ID, blending must be accurate;
=> better lowering Acc/Pos cross-over frequency.
cavities locked independently
(correction signals)
As expected
Next slide
Note: mseism produces excitation of payload pitch and yaw (qx,qz ). Notches implemented to reduce it.
30 mHz crossover N-arm
70 mHz crossover W-arm
EM-MSC

11. wind speed || LVDT_rms increase (observation);
Tilt (f< 100 mHz):
wind speed || LVDT_rms increase (observation);
tilt causes fake acceleration (Losurdo, Passuello, Ruggi);
=> ID causes LVDT_rms increase through in-loop accel. signal.
wind speed
susp displacement
X crossover f = 30 mHz; Z crossover f = 50 mHz
EM-MSC

12. mandatory: reduction of rms displacement of IP at low frequency.
GIPC
mandatory: reduction of rms displacement of IP at low frequency.
main benefits: wind disturbance rejection, lock acquisition, duty-cycle.
Once the ITF is locked, the mirror position, provided by the Global control, can be used instead of Local LVDT.
GC (reconstructed z)
Tested at step 4
WI,NI fx=30 mHz
WE,NE,BS,PR fx= 70 mHz
WI,NI Tower frames
(LVDT vs ground)
EM-MSC
pruggi

13. BS,PR,NE under GIPC, fx =70 mHz all
EM-MSC

14. EM-MSC

15. EM-MSC

16. EM-MSC

17. Performance weakness of some features
12/6/2018
MSC “open” issues
Development of better operation interfaces to facilitate more flexible tests of strategies and new implementations
Performance weakness of some features
- visual interface including F7 and V damping (this week design session)
x and tz local control damping (this week one shift on this topic)
“soft download” facility to allow quiet and repeatable swap between
DSP implementations to cope with extreme environmental situations
EM-MSC
wwwwwww

18. Performance weakness of some features
12/6/2018
MSC “open” issues
Development of better operation interfaces to facilitate more flexible tests of strategies and new implementations
Performance weakness of some features
- visual interface including F7 and V damping (this week design session)
x and tz local control damping (this week one shift on this topic)
“soft download” facility to allow quiet and repeatable swap between
DSP implementations to cope with extreme environmental situations
EM-MSC
wwwwwww

19. WSR6 DECISIONS TAKEN BEFORE THE RUN
12/6/2018
DECISIONS TAKEN BEFORE THE RUN
Spikes related to V-damp at WE occurred the Thursday night
IB V-damp was implemented on Friday morning
50 mHz-peaked seismic bump was present in the afternoon
V-damp long susp not tested under all mseismic conditions
Operator-level switch for V-damp was not designed yet
Signals flags to decide about V-damp ON/OFF not studied yet
V-damp OFF for the run
EM-MSC
wwwwwww

20. IB: V-damp Implementation of V-damp for IB suspention EM-MSC-090107
12/6/2018
Implementation of V-damp for IB suspention
EM-MSC
wwwwwww

21. IB: V-damp
12/6/2018
Just before WSR6…
EM-MSC
wwwwwww

22. WE: V-damp Problem of WE V-damp before WSR6 Under investigation
12/6/2018
WE: V-damp
Problem of WE V-damp before WSR6
Under investigation
EM-MSC
wwwwwww

23. V-damp to be completed and interfaced with the operation
12/6/2018
Conclusions
V-damp to be completed and interfaced with the operation
Fight against wind and mseism going on (3 shifs/week rquested):
measurements, modeling, tests.
Software interfaces to facilitate operator and shifter actions under development
Performance checkups and maintenance going on
EM-MSC
wwwwwww

24. F7 F7 damping ty implemented in 6 towers LC and AA filters can with
12/6/2018
F7 damping ty implemented
in 6 towers
LC and AA filters can with
no 16 mHz.
handle to improve damping
performance VS payload
motion.
other degrees of freedom ?
EM-MSC
wwwwwww

25. Vdamp vertical damping (y) implemented in 6 towers
basically the same filter used for horizontal ID 70 mHz).
only top sensor used (F0)
mseism rms reduction
(NS-NS Horizon > 0
last stormy weather..).
gain optimization
under study
short towers ?
(this week)
EM-MSC

26. Vdamp vertical damping (y) implemented in 6 towers
basically the same filter used for horizontal ID 70 mHz).
only top sensor used (F0)
mseism rms budget
reduction in critical
weather conditions
(lock during last night
storm)
short towers ?
(next step,
probably, urgent)
EM-MSC

27. GIPC Tested using all GC signals (PR,BS,NE,WE) at steps 1, 4, 12
yesterday night data under study
> Mandatory issue:
reduction of seismic (sea) re-injection
> A shift is following
EM-MSC

28. step 11
V-damp ON/OFF: 6 suspensions
EM-MSC

29. step 11 V-damp ON/OFF one-by-one and OFF/ON All No crucial Improvement
O-B-O
OFF
ALL OFF
ALL ON
No crucial
Improvement
during OBO
Test.
Clear
Improvement
All OFF/ON
Relationship
with
Angular
fluctuations
EM-MSC

30. step 11
V-damp ON/OFF one-by-one and OFF/ON All
EM-MSC

31. storm+GIPC step 12 Next improvements and studies A major effort
necessary at LF
during stormy
weather!
Note: preliminary
version of GIPC
And gain mistake
Of IP reallocation
@ WE.
EM-MSC

32. mseism VS tilt
EM-MSC

33. cavities locked independently
mseism ( ) mHz:
relevant LVDTs seismic component in ID, blending must be accurate;
=> better lowering Acc/Pos cross-over frequency.
cavities locked independently
(correction signals)
As expected
Next slide
Note: mseism produces excitation of payload pitch and yaw (qx,qz ). Notches implemented to reduce it.
30 mHz crossover N-arm
70 mHz crossover W-arm
EM-MSC

34. wind speed || LVDT_rms increase (observation);
Tilt (f< 100 mHz):
wind speed || LVDT_rms increase (observation);
tilt causes fake acceleration (Losurdo, Passuello, Ruggi);
=> ID causes LVDT_rms increase through in-loop accel. signal.
wind speed
susp displacement
X crossover f = 30 mHz; Z crossover f = 50 mHz
EM-MSC

35. mandatory: reduction of rms displacement of IP at low frequency.
GIPC
mandatory: reduction of rms displacement of IP at low frequency.
main benefits: wind disturbance rejection, lock acquisition, duty-cycle.
Once the ITF is locked, the mirror position, provided by the Global control, can be used instead of Local LVDT.
GC (reconstructed z)
Tested at step 4
WI,NI fx=30 mHz
WE,NE,BS,PR fx= 70 mHz
WI,NI Tower frames
(LVDT vs ground)
EM-MSC

36. BS,PR,NI under GIPC, fx =70 mHz all
EM-MSC