siesta for virgo locking experience l. barsotti university of pisa – infn pisa on behalf of the...
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SIESTA for Virgo locking experience
L. BarsottiUniversity of Pisa – INFN Pisa
on behalf of the
Virgo Locking Group
Cascina, March 16th 2004 Simulation Workshop
OutlinesOutlines
Commissioning of the first 3–km cavity
Recombined mode
Full Virgo
Other activities in parallel
North Cavity Optical SchemeNorth Cavity Optical Scheme
B1p
T=8%
T=50 ppmT=12%
6 W
B5
B7
PR, WI, WE mirrors misalignedWE
WI
NENIBS
PR
Commissioning of the North CavityCommissioning of the North Cavity
Feedback characterization:
• optical gain
• open loop transfer function
Analysis of the lock algorithm efficiency
• linearized error signal
• no linearized error signal
Comparison with real data (C1, C2 runs)
Real suspensions, real actuators, real photodiodes, computational delays included in the simulation
North Cavity Control SchemeNorth Cavity Control Scheme
B1pT=8%
B7
NENIBSPR
Hz
| Gain
|
frequency
B7_DCB1p_demod
Lock Acquisition
Linearized error signal:
1/m 102.4 8Optical Gain:Optical Gain: Measured
Simulated
Transfer Function Open LoopTransfer Function Open Loop
simulatedmeasured
Gain
Phase
M
G
zErrzCorr
noise
Lock Algorithm Efficiency Lock Algorithm Efficiency
Lock almost always acquired at the first trial
C1 run data : Several lock events collected locking and delocking the cavity
linearized error signal
Lock Algorithm Efficiency Lock Algorithm Efficiency
Failed locking attempt v ~ 12.5
m/s
8 m/s: maximum velocity
for the lock acquisition
success
10
33
m
Fv
λαBv
BΔt
MAXMAX
MAX
2
2
1
sμm
sμm
Constraints on the velocity according to the theory:
Gain due to the linearization:
~ 10
Lock Algorithm EfficiencyLock Algorithm Efficiency
With velocity lower than 10 m/s lock at the first attempt
With velocity higher than 10 m/s lock at the second attempt
Lock failed
Sweep at 12 m/s :
Lock event
Lock Algorithm Efficiency Lock Algorithm Efficiency
Failed locking attempts
not linearized error signalC1 data
Simulation
SIESTA link to real time controlSIESTA link to real time control
SIESTA
Control signalsPhotodiodes signals
Algorithms running in the global control
SIESTA link to real time controlSIESTA link to real time control
Control signalsPhotodiodes signals
Algorithms running in the global control
VIRGO
Recombined Optical SchemeRecombined Optical Scheme
B1
T=8% B5
B7
B8
B2
WE
NENI
WI
BSPR
PR mirror misaligned
Recombined modeRecombined mode
2 Steps locking strategy:
•sensing matrix
•procedure to find experimentally the algorithm parameters from simple optical systems
3 Steps locking strategy
•sensitivity curve
•comparison with real data
Linear locking
Reconbined Reconbined 2 Steps2 Steps Control Scheme Control Scheme
B1
B5
B7
B8
B2
north cavity controlled with B5
west cavity and michelson controlled at
the sime time
hLength_mic
tLength_wes
B2_quad
B1p_quad
10
2π1
Theorical optical matrix:
hLength_mic
tLength_wes
B2_quad
B1p_quad
10.08
0.041
Optical matrix measured by Siesta:
Michelson and West cavity controlled with the symmetric (B2_quad) and the antysimmetric signal (B1p_quad)
Sensing matrix
Locking simulation – North cavity
Locking
Locking simulation – Mich & WestPowers Lengths
Triggers
Corrections
B7_demod
B1p_demod
B2
North arm
West arm
B5
B8_demod
switch from B1p to B1 after the lock acquisition
Recombined Recombined 3Steps 3Steps Control SchemeControl Scheme
Lock acquisition -Lock acquisition - simulationsimulation
“Simple” simulation:
real suspensions and actuators
Lock acquisition -Lock acquisition - simulationsimulation
First lock acquisition27th February
Locking event At 3.25 am
Sensitivity - Sensitivity - simulationsimulation
Improvement:
real photodiodes (electronic noise, shot noise)
SensitivitySensitivity
Simulated
Measured
Switch to the linear locking state
west
nord
mich
4.3e34.3e31.8e2
2.6e42.6e40
10384
d1p_quad
d2_phase
d2_quad
Optical matrix:
d2_quad
d2_phase
d1p_quad
MICH
CARM
DARM
d1p_quad
d2_phase
d2_quad
4-1.16e5-1.9e0
4-1.16e-5-1.9e0
002-1.19e
west
nord
mich
Inverse optical matrix:
⊗
B1p_quadB2_quad
North arm
West arm
B2_phase
Linear Locking Linear Locking Control SchemeControl Scheme
Linear lock of the recombined
Simulation
Full Virgo Optical SchemeFull Virgo Optical Scheme
B1
B5
B7
B8
B2
WE
NENI
WI
BSPR
Multi–states approach (LIGO scheme)
Dynamical inversion of the optical matrix
Lock acquisition of full Virgo Lock acquisition of full Virgo
Lock acquisition of full VirgoLock acquisition of full Virgo
Something more…Something more…
Modal simulationModal simulation
Longitudinal local control optimizationLongitudinal local control optimization
Spikes removalSpikes removal
Modal simulation
High order modes (n + m ≤ 5 )
• compromise with the computational time 1 sec @ 20
kHz ⇒ 45 sec
Check with other codes in progress
0.113
misalignment of 2 rad in y of the curve mirror
Something more…Something more…
Modal simulationModal simulation
Longitudinal local control optimizationLongitudinal local control optimization
Spikes removalSpikes removal
Optimization of the z damping loop – I
10 sec
zCorr zMirrorm
Hz
Unity gain @ 0.65 Hz
measured
Open loop transfer function
Damping time sec
Optimization of the z damping loop – II
simulated
Open loop transfer function
Critical damping @
1.45 Hz
Hz
mV
zCorr zMirror
2 sec
Optimization of the z damping loop – III
measured after the optimization
mV
~ 2 sec
zCorr zMirror
Guadagno open loop
Hz
Critical damping @
1.45 Hz
Something more…Something more…
Modal simulationModal simulation
Longitudinal local control optimizationLongitudinal local control optimization
Spikes removalSpikes removal
Spikes removal Spikes removal
Spikes removalSpikes removal
Rearrange the algo:
Error signal derivative window integrator window
Other activity: Hierarchical controlHierarchical control
marionetta
reference mass
mirror
z
Control from the reference mass
Control from the marionetta
Transfer function betweeen force on steering filter and z movement of the
mirror
preliminary results
wwwcascina.virgo.infn.it/collmeetings/presentations/Mar2004/Fiori_11Mar04_MarioLockSim.ppt
ConclusionsConclusions
Siesta: fundamental tool for locking studies
Link to the real time control system
Work in parallel with other groups to improve the simulation (suspensions, alignment)
Noise analysis