qd0 stabilisation update (since last update in mdi) a.jeremie a.badel, b.caron, r.lebreton,...
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QD0 stabilisation update(since last update in MDI)
A.JeremieA.Badel, B.Caron, R.LeBreton, J.Lottin,
J.Allibe, G.Balik, J.P.Baud, L.Brunetti, G.Deleglise
QD0 stabilisation update(since last update in MDI)
A.JeremieA.Badel, B.Caron, R.LeBreton, J.Lottin,
J.Allibe, G.Balik, J.P.Baud, L.Brunetti, G.Deleglise
Got a permanent position at LAPP
New EuCARD post-doc
What has been done
• Characterize the stabilisation system• Develop a model for the components• Develop control loops• First test on set-up
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Correction scheme
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Input noise External sensor
Sensor noise Controller
Dynamical model of system
++ +
+
In order to optimize the controller, we need to get the maximum of information on the components in the system
Phase 1 : Stabilisation system behaviour
100
101
102
103
104-10
01020304050
Gain dB
100
101
102
103
104
-1500
-1000
-500
0
PhaseIntrinsic resonances if change of phase by 90°: other peaks just from boundary conditions => 2 resonance peaks just below 2kHz and near 4kHz.
First intrinsic resonance frequency near 2kHz : experimental and theoretical values agree.
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Frequency (Hz)
Model for the components
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Sensor
Mechanics
Global system
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Test conditions
Capacitive sensors used for setting-up the systemFeedback loop with accelerometers: one on “ground” other on top of systemNo mass on systemTo maximize signal for test:
Excitation: high frequency “hammer hit” (so high frequency range)Cut “low-frequency” range from test
Control testratio of transfer functions
0 100 200 300 400 500 600 700 800 900 1000-25
-20
-15
-10
-5
0
5
10
15
Fréquence (en Hz)
Ma
gn
itu
de
FF
T T
ran
sm
iss
ion
(e
n d
B)
Fonction de Transfert en transmission
Open loop
Closed loop
Simulation with closed loop
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Next steps
• Other feedback loops are available that work well in simulation, but need to better understand some “low-frequency” experimental problems encountered
• Characterize sensor in more detail• Excite with “ground motion” instead of
hammer• Add QD0 dummy mass
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UR
GE
NT
!
• Enjoy the Holliday season!
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