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40m Log |
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Mon Mar 8 12:01:02 2021, Paco, Anchal, Summary, training, Investigate how-to XARM locking
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Mon Mar 8 12:40:35 2021, gautam, Summary, training, Investigate how-to XARM locking
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Mon Mar 8 19:22:56 2021, rana, Summary, SUS, IMC suspension characterization
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Thu Mar 11 08:13:24 2021, Paco, Anchal, Update, SUS, IMC First Free Swing Test failed due to typo, restarting now
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Tue Mar 16 19:13:09 2021, Paco, Anchal, Update, SUS, First success in Input Matric Diagonalization 
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Wed Mar 17 11:57:54 2021, Paco, Anchal, Update, SUS, Tested New Input Matrix for MC1 
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Wed Mar 17 16:30:46 2021, Anchal, Update, SUS, Normalized Input Matrices plotted better than SURF students 
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Thu Mar 18 09:18:49 2021, Paco, Anchal, Update, SUS, Testing of new input matrices with new data 
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Thu Mar 18 12:46:53 2021, rana, Update, SUS, Testing of new input matrices with new data
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Fri Mar 19 10:49:44 2021, Paco, Anchal, Update, SUS, Trying coil actuation balance
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Mon Mar 22 11:57:21 2021, Paco, Anchal, Update, SUS, Trying coil actuation balance 
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Mon Mar 22 15:10:00 2021, rana, Update, SUS, Trying coil actuation balance
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Mon Mar 22 19:07:50 2021, Paco, Anchal, Update, SUS, Trying coil actuation balance 8x
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Tue Mar 23 09:16:42 2021, Paco, Anchal, Update, Computers, Power cycled C1PSL; restored C1PSL 
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Wed Mar 24 09:23:49 2021, Paco, Update, SUS, MC3 new Input Matrix
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Thu Mar 25 11:46:31 2021, Paco, Anchal, Update, SUS, MC2 Coil Balancing updates   
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Thu Mar 25 15:31:24 2021, gautam, Update, IOO, WFS servos
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Fri Mar 26 11:54:37 2021, Paco, Anchal, Update, SUS, MC2 Coil Balancing updates
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Mon Mar 29 10:44:51 2021, Paco, Anchal, Update, SUS, MC2 Coil Balancing updates 
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Mon Mar 29 17:11:54 2021, gautam, Update, SUS, MC2 Coil Balancing updates
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Mon Mar 29 17:34:52 2021, rana, Update, SUS, MC2 Coil Balancing updates
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Wed Mar 31 22:58:32 2021, Anchal, Paco, Update, SUS, MC2 Coil Balancing Test
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Thu Apr 1 13:56:49 2021, Anchal, Paco, Update, SUS, MC2 Coil Balancing Test Results  
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Thu Apr 1 18:01:06 2021, Anchal, Paco, Update, SUS, MC2 Coil Balancing Test Results Success??  
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Thu Apr 1 18:48:45 2021, gautam, Update, SUS, MC2 Coil Balancing Test Results Success??
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Thu Apr 1 21:13:54 2021, Anchal, Update, SUS, Matrix results, new measurement set to trigger
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Fri Apr 2 14:51:20 2021, Anchal, Update, SUS, Bug found, need to redo the balancing
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Tue Apr 6 18:46:36 2021, Anchal, Paco, Update, SUS, Updates on recent efforts
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Wed Apr 7 17:38:51 2021, Anchal, Update, SUS, Trying to uncouple only PIT and YAW first    
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Thu Apr 8 17:04:43 2021, Anchal, Paco, Update, SUS, First Successful Coil Balancing  
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Fri Apr 9 13:13:00 2021, Anchal, Paco, Update, SUS, Faster coil balancing 
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Fri Apr 9 17:41:12 2021, rana, Update, SUS, Faster coil balancing
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Mon Apr 12 10:07:35 2021, Anchal, Update, SUS, What's F2A??
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Tue Apr 13 09:51:22 2021, rana, Update, SUS, What's F2A??
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Wed Apr 14 17:53:38 2021, Anchal, Update, SUS, Plan for calculating filter banks for output matrix aka F2A aka F2P
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Thu Apr 15 11:41:43 2021, Anchal, Update, SUS, Proposed filters for output matrix aka F2A aka F2P
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Fri Apr 16 11:36:36 2021, Anchal, Paco, Update, SUS, Tested proposed filters for POS colum in MC2 output matrix    
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Fri Apr 16 15:47:58 2021, rana, Update, SUS, Tested proposed filters for POS colum in MC2 output matrix
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Mon Apr 19 12:18:19 2021, Anchal, Paco, Update, SUS, Tested proposed filters for POS colum in MC2 output matrix  
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Tue Apr 20 10:52:49 2021, Anchal, Paco, Update, SUS, AC gain coil output balancing for IMC   
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Tue Apr 20 18:19:30 2021, Anchal, Update, SUS, MC2 coil balanced at DC  
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Wed Apr 21 11:38:27 2021, Anchal, Paco, Update, SUS, MC2 Damping Gains Optimized 
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Wed Apr 21 15:50:01 2021, Anchal, Paco, Update, SUS, MC2 Suspension Optimization summary
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Wed Apr 21 18:49:29 2021, rana, Update, SUS, MC2 Suspension Optimization summary
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Thu Apr 22 08:50:21 2021, Anchal, Update, SUS, MC2 Suspension Optimization summary
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Mon Apr 26 18:55:39 2021, Anchal, Paco, Update, SUS, MC2 F2A Filters Tested  
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Tue Apr 27 10:05:28 2021, Anchal, Paco, Update, SUS, MC1 and MC3 F2A Filters Tested   
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Wed Apr 28 10:56:10 2021, Anchal, Paco, Update, SUS, IMC Filters diagnosed 7x
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Wed Apr 28 17:09:11 2021, Anchal, Update, SUS, Tuned Suspension Parameters uploaded for long term behavior monitoring
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Thu Apr 29 10:52:56 2021, Anchal, Update, SUS, IMC Trans QPD and WFS loops step response test 
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Thu Apr 29 18:53:33 2021, Anchal, Update, SUS, IMC Suspension Damping Gains Test  
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Mon May 3 16:24:14 2021, Anchal, Update, SUS, IMC Suspension Damping Gains Test Repeated with IMC unlocked  
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Wed May 5 09:04:47 2021, Anchal, Update, SUS, New IMC Suspension Damping Gains uploaded for long term testing
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Wed May 12 11:45:13 2021, Anchal, Paco, Summary, SUS, New IMC Settings are miserable  
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Wed Jun 2 09:43:30 2021, Anchal, Paco, Summary, SUS, IMC Settings characterization   
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Wed Jun 2 16:20:59 2021, Anchal, Paco, Summary, SUS, IMC Suspension gains reverted to old values
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Sat May 15 14:54:24 2021, gautam, Update, SUS, IMC settings reverted
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Thu May 20 10:35:57 2021, Anchal, Update, SUS, IMC settings reverted
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Thu Apr 22 12:17:23 2021, Anchal, Paco, Update, SUS, MC1 and MC3 Suspension Optimization Summary
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Thu Apr 22 14:22:39 2021, gautam, Update, SUS, Settings restored
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Thu Apr 22 15:36:54 2021, Anchal, Update, SUS, Settings restored
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Thu Apr 22 17:04:17 2021, gautam, Update, SUS, Settings restored
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Sat Apr 10 10:07:47 2021, rana, Update, SUS, Faster coil balancing
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Fri Apr 2 15:22:54 2021, gautam, Update, SUS, Matrix results, new measurement set to trigger
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Sun Mar 28 14:16:25 2021, Anchal, Summary, SUS, MC3 new Input Matrix not providing stable loop
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Mon Mar 29 17:07:17 2021, gautam, Summary, SUS, MC3 new Input Matrix not providing stable loop
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Thu Mar 18 13:12:39 2021, gautam, Update, Computer Scripts / Programs, Omnigraffle vs draw.io
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Message ID: 16007
Entry time: Thu Apr 8 17:04:43 2021
In reply to: 16005
Reply to this: 16009
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Author: |
Anchal, Paco |
Type: |
Update |
Category: |
SUS |
Subject: |
First Successful Coil Balancing |
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Today, we finally crossed the last hurdle and got a successful converging coil balancing run. 
What was the issue with POS?
- Position of the MC2 mirror is being sensed using C1:IOO-MC_F_DQ channel which is proportional to the resonant frequency of the locked IMC.
- However, this sensor is always 180 degrees out of phase of our actuator, the coils.
- When the coils push the mirror forward, the length of the cavity actually decreases.
- We added an extra option of providing a sign to the sensors such that -1 will be multiplied to sensed values for sensors which measure in opposite direction to the actuation.
- This is important, because the feedback is applied to the coil output matrix assuming a particular direction of acctuation.
- When we gave negative sign for the position sensor, it all started making sense and the algorithm started converging.
First run parameters:
- We used binwidth of 0.25 Hz and duration of excitation as 41s. This would give welch and csd averaging of 19. We used median averaging to ignore outliers.
- This iteration was run after PIT and YAW were separetly uncoupled before. We'll post a clean start to end run results in near future.
- The iteration works in following manner:
- Define a constant coil matrix C = [[1, 1, 1], [1, 1, -1], [1, -1, 1], [1, -1, -1]] which is ideal coil output matrix.
- In each iteration, the output matrix Ok is defined as (note @ is the matmul operator):
Ok = C @ Ak
where Ak is a 3x3 matrix. A-1 is identity matrix.
- At the end of each iteration, a sensing matrix is calculated in dimensions sensedDOF x excitedDOF, Sk
- For next iteration, Ak+1 is calcualted by:
Ak+1 = Ak - b * (Sk - I)
where I is the identity matrix.
- At convergence, the sensing matrix would become same as identity and matrix A will stop updating.
- For this run, we kept the parameter b to be 0.05. This is similar to the KP parameter in PID loops. It should be between 0 and 1.
- Since b value was small enough to allow for convergence from the inital point, but later it slowed down the process a lot.
- Ideally, we should figure out a way to increase this paramter when the coil has been balanced somewhat, to increase the speed of the algorithm.
- Secondly, we have a code which excites all DOFs at different frequencies directly using excitation channels in coil output matrix using awg.py. But for some reason, the excitation channel for 4th row in the output matrix column only connects intermittantly. Because of this, we can't use this method reliably yet. We can investigate more into it if suggested.
Balancing characteristics:
- Attachment 1 shows how the distance of sensing matrix falls as iterations increase. We only ran for 50 iterations.
- Attachment 2 shows how different off-diagonal terms of sensing matrix decreased.
- Note that POS -> PIT, POS -> YAW and PIT-YAW have settled down to the noise floor.
- The noise floor can be improved by increasing the excitation amplitude and/or increasing the duration of measurement.
- Attachment 3 shows the evolution of sensing matrix as iterations move.
Final balanced output matrix:
Final balanced output coil matrix for MC2
POS |
PIT |
YAW |
COILS |
1.02956 |
1.13053 |
1.19116 |
UL |
1.01210 |
1.09188 |
-0.74832 |
UR |
0.98737 |
-0.85502 |
0.70485 |
LR |
0.96991 |
-0.89366 |
-1.23463 |
LR |
Final Sensing Matrix
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Exc POS |
Exc PIT |
Exc YAW |
Sens POS |
1 |
-2.96e-2 |
8.00e-3 |
Sens PIT |
8.58e-4 |
1 |
-4.84e-3 |
Sens YAW |
5.97e-4 |
-1.15e-3 |
1 |
Code features and next:
- Majority of the code is in two files: scripts/SUS/OutMatCalc/MC2crossCoupleTest.py and scripts/SUS/OutMatCalc/crossCoupleTest.py .
- The code runs from start to end without human involevement and restores the state of channels in any case (error, kyboard interrupt, end of code) using finally statement.
- Currently, each excitation is done one at a time through LockIn1. As mentioned above, this can be sped up 3 times if we get the awg.py to work reliably.
- The complete code is in python3 and currently is run through native python3 on allegra (a new debian10 workstation with latest cds-workstation installed).
- The code can be easily generalized for balancing any optic. Please let us know if we should work on making the generalized optic.
- We're also working on thinking about increasing b as iterations move forward and the error signal becomes smaller.
- We can also include the uncertainty in the Sensing matrix measurement to provide a weighted feedback. That way, we can probably increase b more.
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