S. Gibson FSI Offline Analysis 9 th October 2003 1 FSI Alignment: Offline Analysis Overview ATLAS...
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Transcript of S. Gibson FSI Offline Analysis 9 th October 2003 1 FSI Alignment: Offline Analysis Overview ATLAS...
S. Gibson FSI Offline Analysis 9th October 20031
FSI Alignment:FSI Alignment: Offline Analysis Offline Analysis
Overview
ATLAS Group, University of OxfordStephen Gibson, Danny Hindson, Pawel Bruckman de Renstrom,
Paul Coe, Tony Weidberg
• Reminder of FSI
• What FSI provides
• Node reconstruction
• Analysis approaches:
• Reverse FEA
• Eigenmode decomposition
S. Gibson FSI Offline Analysis 9th October 20032
SCT monitored with FSI geodetic gridsSCT monitored with FSI geodetic grids
SemiConductor Trackermonitored using a
geodetic grid of 842 length measurements.
Forward SCT grid
Barrel SCT grid
S. Gibson FSI Offline Analysis 9th October 20033
FSI System Installed on Barrel 3FSI System Installed on Barrel 3
FSI grid
nodes
S. Gibson FSI Offline Analysis 9th October 20034
Barrel FSI grid node: “Scorpion”Barrel FSI grid node: “Scorpion”
Pre-alignment jig Installed on barrel
S. Gibson FSI Offline Analysis 9th October 20035
Endcap FSI Grid Node: “Viking”Endcap FSI Grid Node: “Viking”
S. Gibson FSI Offline Analysis 9th October 20036
Endcap FSI Grid Node: “Viking”Endcap FSI Grid Node: “Viking”
Now in pre-alignment jig – see hardware tour
S. Gibson FSI Offline Analysis 9th October 20037
Endcap FSI: Pre-alignment jigEndcap FSI: Pre-alignment jig
S. Gibson FSI Offline Analysis 9th October 20038
What does FSI provide?What does FSI provide?
• One FSI scan provides a set of precise length measurements between grid nodes (<1micron).
• Not absolute but relative measurements – interested in differences between scans.
Timescale:
• Each laser scan will take a few minutes (to generate the raw data).
• Rate of scans will depend on: Available processor resources. Data storage:
• Interferometer data ~ 1 GB per scan.• Length data ~ only 10 kB per scan.
Demand for FSI data (during a fill/ between fills/ shutdowns).
• Frequent measurements allow short time scale distortions to be followed and corrected.
• Access to low spatial frequency modes of tracker distortion (sagitta).
S. Gibson FSI Offline Analysis 9th October 20039
Alignment System CalibrationAlignment System Calibration
scanning head
Initial ModuleCo-ordinates
Initial Node Positions
X-ray survey
FSI scan
FSI System Calibrationsimultaneous
S. Gibson FSI Offline Analysis 9th October 200310
Analysis of FSI dataAnalysis of FSI data
Interferometer data analysis:
• This data consists of sinusoidal fringes from each grid line interferometer (for both lasers) + gas measurements. Total ~ 1GB per scan.
• PC farm will process data in quasi-real-time to determine the set of lengths for each scan.
• Time to process each scan?
• Result is 842 lengths kept on record.
How to use these 842 lengths?
S. Gibson FSI Offline Analysis 9th October 200311
Analysis of FSI dataAnalysis of FSI data
FSI Grid Lengths
Reconstruction
ModuleCo-ordinates
Interpolation
Node DoF
Want to determine parameters of a model.
Model to bedefined
Reconstruction software.
Node reconstruction already shown for simple prototype grids.
ATLAS grid simulations: see next slide.
Interpolation process:
Shape parameterisation
FEA: barrel and disc eigenmodes
Check with ESPI studies
Calibration from initial X-ray survey
S. Gibson FSI Offline Analysis 9th October 200312
Reconstruction Software StatusReconstruction Software Status
• Preliminary investigations: A. Fox-Murphy Thesis
Final grid designs:• Barrel grid error propagations:
Inner barrel grid quadrant Single barrel grid End-flange grid Full Barrel SCT grid
• Endcap grid error propagations: Initial simulation: ATL-IS-AP-0054. Improved final design described in ATL-IS-ES-0081.
• Node reconstruction already shown for simple prototype grids.
• Will extend simulations of ATLAS grids to allow node reconstruction. (PPARC fellowship)
Simulated: ATL-IS-ES-0026
In progress: S. Gibson Thesis(to be published)
Simulated: S. Gibson Thesis
S. Gibson FSI Offline Analysis 9th October 200313
Precise Grid MeasurementsPrecise Grid Measurements
Precise three dimensional
node reconstruction
1m
Well within ATLAS 10m requirement
S. Gibson FSI Offline Analysis 9th October 200314
Endcap Grid Reconstruction SimulationEndcap Grid Reconstruction Simulation
• Error in reconstructing the translational DoF of each disc with respect to the first disc.
S. Gibson FSI Offline Analysis 9th October 200315
Endcap grid: reconstruction errorsEndcap grid: reconstruction errors
• Error in reconstructing the translational DoF of each disc with respect to a reference disc.
• ‘Pinch’ effect: on redefining the reference disc, the errors change as shown.
• Smallest errors when ‘held’ at centre (disc 6).
• Reconstructed endcap shape should be model independent – effect is simply a global coordinate transformation.
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Interpolation ProcessInterpolation Process
• Output from reconstruction doesn’t have to be x,y,z of each FSI node. (Rather fitted DoF defined in model).
• Must provide node DoF in format compatible with interpolation process.
• Some possible formats: FSI node x,y,z (for 3 independent frames A,B,C). 6 DoF of objects that contain nodes, with further internal
DoF. (barrel SCT: contains 4 barrels: barrel distortion; endcap: contains 9 discs: disc distortion).
• Need to incorporate track data.• Two approaches so far considered for offline
analysis: Reverse FEA Eigenmode decomposition (shape parameterisation)
S. Gibson FSI Offline Analysis 9th October 200317
Interpolation processInterpolation process
• Shape parameterisation Fit eigenmodes of SCT support
structure to FSI grid node positions to determine barrel shape.
• Reverse FEA Insert FSI node positions to FEA
model and solve directly for module coordinates. ESPI
Test process experimentally with independent structural monitoring using:
Electronic Speckle Pattern Interferometry.
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Reverse FEAReverse FEA
1. Apply realistic force to barrel eg gravity with missing support
3. Run reverse FEA to interpolate positions of other FEA nodes
2. Retain positions of FSI nodes only. Fix the positions of these nodes
Interpolated positionsActual positions
S. Gibson FSI Offline Analysis 9th October 200319
Reverse FEA: residualsReverse FEA: residuals
This assumes elastic properties of barrel are known perfectly
If rerun with wrong Young’s modulus, wrong Poissons ratio (10% out), mean difference is still <1 micron
S. Gibson FSI Offline Analysis 9th October 200320
• Reconstruction and interpolation process must be checked experimentally.
• Measure lengths of an FSI grid.• Reconstruct nodes and interpolate dummy module positions.• Monitor dummy module positions independently with Electronic
Speckle Pattern Interferometry.
Possible Check with ESPIPossible Check with ESPI
ESPIFSI grid
Distorted barrel
S. Gibson FSI Offline Analysis 9th October 200321
Offline Analysis Method 1Offline Analysis Method 1
ModuleCoords
X24 (assume scanper hour)
Base line Modulecoords
Initial ModuleCo-ordinates
X-ray survey
Reverse FEA
Adjust hit positions
Corrections to module coords
Run track alignment 24 hrs FSI corrected data
A,B,C
FSI Node DoF
TracksDatabase
Inte
rpo
late
in
tim
e?
Timeadjust
modules
Time dep.modules
X24
Time dep.modules
time
S. Gibson FSI Offline Analysis 9th October 200322
Eigenmode DecompositionEigenmode Decomposition
SCT shape (or sub components of it) can be expressed as a sum of eigenmodes. (see next slide)
Spatial frequencyeigenmode
FSI
Time
seconds
minutes
hours
days
months
Tracks
X-ray survey
FEA Module metrology
Module temperature
S. Gibson FSI Offline Analysis 9th October 200323
Offline Analysis Method 2Offline Analysis Method 2
Initial ModuleCo-ordinates
X-ray survey
Global Fit to for eigenmodes
A,B,C
FSI Node DoF
Tracks
DatabaseInterpolate in time?
Time dep.modules
Time dep.modules
time
FEA informatio
n
metrology
S. Gibson FSI Offline Analysis 9th October 200324
Comments/ConclusionsComments/Conclusions
Reconstruction software: Endcap grid fully simulated Barrel grid partially simulated – rest should be done by end
March 2004. Will extend simulations to full reconstruction.
Interpolation• Some initial thoughts, but much to be decided:• Reverse FEA:
Relatively simple. Modular approach. Mechnical constraints added after fit for nodes. Reliability of result?
• Eigenmode decomposition Ideal way to proceed. More difficult to combine all information. Ease of inclusion of mechanical properties? We can improve the model with time.