1. Control of the KAGRA Cryogenic Vibration Isolation System
Koki Okutomi
Sokendai / NAOJ / KAGRA VIS subgroup
R. Takahashi, H. Ishizaki, S. Sato, A. Shoda, T. Sekiguchi, Y. Fujii, T. Miyamoto, T. Ushiba, N. Hirata, K. Hayama, T. Akutsu, Y. Aso, R. Flaminio, R. DeSalvo
GWADW 2017, Hamilton Island

2. Contents KAGRA cryogenic suspension: Type-A SAS
Modal damping control of Type-A SAS
Cryogenic and underground issues
GWADW 2017, Hamilton Island

3. Seismic Attenuation Systems
Type-A
Seismic Attenuation Systems
in KAGRA
Type-B
Type-Bp
GWADW 2017, Hamilton Island

4. Type-A SAS Suspension for arm cavity mirrors Tower (room temperature)
ETMY
ITMY
13.5 m
ITMX
ETMX
Suspension for arm cavity mirrors
Tower (room temperature)
Cryogenic payload
GWADW 2017, Hamilton Island

5. Type-A SAS Suspension for arm cavity mirrors Tower (room temperature)
ETMY
ITMY
13.5 m
ITMX
ETMX
Suspension for arm cavity mirrors
Tower (room temperature)
Cryogenic payload
GWADW 2017, Hamilton Island

6. Features of Type-A SAS Inverted pendulum legs Parallel chain
(Ground)
Parallel chain
Geometric Anti-Spring
(GAS) filters
Platform
Mario-nette
MRM IM TM RM
IRM
Cryogenic payload
GWADW 2017, Hamilton Island

7. Observable DoFs (Tower)
LVDT
Accelerometer
Filter 0
F0 Long., Trans., Yaw
GAS relative Vertical
F0-F1
F1-F2
F2-F3
F3-BF
BF-PF
Filter 1
LVDT
Filter 2
Filter 3
Bottom
Filter
(BF) LVDT
BF 6DoFs
* From ground
or mass relative
Vertical
Yaw
Roll
Longitudinal
Transverse
Next page
Pitch
GWADW 2017, Hamilton Island

8. Observable DoFs (Payload)
Platform
Optical lever
PF Roll, Pitch, Yaw
Optical lever
Photo-sensor
Marionette
- MRM
MN Roll, Pitch, Yaw
MN-MRM 6DoFs
IM - IRM
IM-IRM 6DoFs
Photo-sensor
TM - RM
Optical lever
TM Pitch, Yaw
* From ground
or mass relative
GWADW 2017, Hamilton Island

9. Controllable DoFs Coil-magnet actuator (all) Filter 0 Filter 1
F0 Long., Trans., Yaw
GAS relative Vertical
F0-F1
F1-F2
F2-F3
F3-BF
BF-PF
Filter 1
Filter 2
Coil-magnet actuator (all)
Filter 3
Bottom
Filter
BF 6DoFs
Platform
MN-MRM 6DoFs
MN - MRM
IM-IRM 6DoFs
IM - IRM
TM - RM
TM-RM Long., Pitch, Yaw
GWADW 2017, Hamilton Island

10. F7 LVDT in Adv. Virgo → re-designed for KAGRA
BF LVDT
F7 LVDT in Adv. Virgo → re-designed for KAGRA
GWADW 2017, Hamilton Island

11. Configuration of BF LVDT
Vertical x3
Horizontal x3
GWADW 2017, Hamilton Island

12. Eigenmodes in Type-A ︙ Totally 75 eigenmodes #1: Y whole chain 0th
0.067Hz
0.067Hz
#1: Y whole chain 0th
#2: Y whole chain 1st
#3: T whole chain 0th 　 IP translation
#4: L whole chain 0th
　 IP translation
#5: Y whole chain 2nd
#6: Y whole chain 3rd ︙
Totally
75 eigenmodes #1 #2 #3 #4 #5 #6
GWADW 2017, Hamilton Island

13. Horizontal Actuators Sensors Servo IP LVDT (Only tower part) GAS
Coil-magnet
IP LVDT
Horizontal
(Only tower part)
Coil-magnet
GAS
Coil-magnet
BF LVDT
Servo
Servo
GWADW 2017, Hamilton Island

14. Open-loop TF (F0 Longitudinal)
1st pendulum
0.454 Hz
IP horizontal
0.067 Hz
0th pendulum
0.207 Hz
GWADW 2017, Hamilton Island

15. Open-loop TF (BF Yaw) 0.018 Hz 0.088 Hz 0.120 Hz Whole chain 0th
Whole chain 2nd
0.088 Hz
Whole chain 3nd
0.120 Hz
GWADW 2017, Hamilton Island

16. Vertical Actuators Sensors Servo IP LVDT GAS LVDT BF LVDT Servo
Coil-magnet
IP LVDT
Vertical
Coil-magnet
GAS LVDT
Coil-magnet
BF LVDT
Servo
Servo
GWADW 2017, Hamilton Island

17. Open-loop TF (GAS F0 Vertical)
Whole chain 0th
0.148 Hz …
Whole chain 1st
0.413 Hz
Whole chain 2nd
0.120 Hz
GWADW 2017, Hamilton Island

18. Decay Time (IP + BF + GAS Damping)
Damping Time [sec]
Requirement (< 60 sec.)
GWADW 2017, Hamilton Island

19. Next To-do Sensor blending on IP control
LVDT displacement sensor + Accelerometer
Seismic re-introduction from BF control
EQ-stop mechanical eigenmode analysis
Sensor/Actuator decoupling
Damping strategy in cryogenic payload
GWADW 2017, Hamilton Island

20. Cryogenic and Underground Issues
GWADW 2017, Hamilton Island

21. Impact of Heat Link Seismic noise from HL
Platform
Mario-nette
MRM IM TM RM
IRM
*Old design!!
Seismic noise from HL
Heat-link suspension (double pendulum)
GWADW 2017, Hamilton Island

22. Wire Shrinkage ~ 1.5 mm ~ 0.1 mm ✔ Total wire shrinkage for each chain
Platform
Mario-nette
MRM IM TM RM
IRM
Total wire shrinkage for each chain
~ 1.5 mm
Relative shift
~ 0.1 mm ✔
* Rough estimation
Maraging
CuBe
CuBe
CuBe
Sapphire
CuBe
GWADW 2017, Hamilton Island

23. Temperature Gradient Temperature sensor 300 K Bottom Filter Cryostat
GWADW 2017, Hamilton Island

24. Seismic in Underground
0.2 Hz
[1x10-7 ~ 3x10-6 ] m/Hz1/2
GWADW 2017, Hamilton Island
A. Shoda, Poster in GWADW 2016

25. Temperature in Underground
PSL
Center
X-end
Y-end
A. Shoda, Poster in GWADW 2016
GAS thermal drift ➢ Δz / ΔT = 0.69 mm [mm/K]
GWADW 2017, Hamilton Island

26. Practical Problem on Installation
Not
accessible
Release Sensor
(ON/OFF)
JGW-D
Dummy Payload
GWADW 2017, Hamilton Island

27. How Is Type-A SAS Now? F1 is sitting on the 2nd floor chamber
Klog 2737
F1 is sitting on the 2nd floor chamber
GWADW 2017, Hamilton Island

28. Summary KAGRA Cryogenic suspension: Type-A SAS
Under installation
Damping control design for tower ✔
Tuning of the control along w/ noise estimation
Cryogenic and underground issues
Vibration analysis of the heat links
Treatment of cooling effects on the suspension
Implementation of underground monitors into control
GWADW 2017, Hamilton Island

29. Backup Slides
GWADW 2017, Hamilton Island

30. Stage Configuration Coordinate difinition Vertical Yaw Roll
13.5 m F3
Yaw
Roll BF
Longitudinal
Transverse
Pitch PF
Cryogenic
Payload MT
MRM IM
IRM TM RM
GWADW 2017, Hamilton Island

31. Bottom Filter LVDT Sensor / Actuator
(suspended stage)
Sensor / Actuator
Primary coil
10 kHz modul.
Displacement sensor of the primary coil
Local
Oscillator
Secondary
coils
Displacement
signal
(Ground-side)
Mixer
Low-pass
GWADW 2017, Hamilton Island

32. Bottom Filter LVDT Sensor / Actuator Coil-magnet actuator
(suspended stage)
Sensor / Actuator
Magnet
Coil-magnet actuator
Driving-frequency separation
Sensor: 10 kHz (high)
Actuator: < 10 Hz (Low)
Secondary
coils
Coil Driver
Actuation signal
(Ground-side)
GWADW 2017, Hamilton Island

33. Yend X Test Schedule end Apr. May Jun. Jul. Aug. Sep. Oct.
Installation
Test w/ DP
In air, Room temp
5/16 – 6/11
Full hanging test & Cooling
w/ sapphire dummy
6/12 – 9/14
VIS Installation
Test w/ DP
In vaccum,
Room temp
8/1 – 10/15
GWADW 2017, Hamilton Island

34. KAGRA EYV Room

35. Vertical Chamber Opened

36. Future update System identification test
Real-system modeling
Implementation of Kalman filter
Estimation of system parameters
Feedback design optimization with machine learning
LQ regulator + Machine learning → weight optimization
Feedforward control with underground environmental monitors
GWADW 2017, Hamilton Island