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==== Report for week of 1/14 ==== * Etc * BS * SR2 * Hirata-san helped with installing the obelisk on the LBB, and added counterweights to get the LBB level and at the right height for the first rough alignment. However the springs were still at or near the top stops, so he later pulled down the LBB with excess mass, locked the blades at the bottom of their range and reset the LBB rods and damping magnet ring, aiming off by 10 mm so that it would be correct when the LBB was allowed to rise. However he left it pressed down for now so that Hirose-san could apply FC. Early next week he will release it and do the final ballasting. * SR3 * Enzo installed IM damping filters. * Mark installed a BIO Converter for the stepper remote enable (which will eventually also be used for the WD). * Fabian researched buoyancy compensation and pre-applied as much as possible. The total compensation needed is 0.19 mm for F0, 0.48 mm for SF and 0.46 mm for BF, total 1.23 mm. * SRM * Mirapro helped us with the camera viewport issue by giving us a gasket of the same type but a different brand from their stock, which snapped easily into place. We then installed the viewport on the tank. * Fabian calibrated the F0 FR. |
==== Report for the week 6/24 (Written by Terrence and Fabian) ==== * Type B watchdog/DACKILL is split for tower and payload. Now, tripping the payload watchdog will only trigger the payload DACKILL while tripping the tower watchdog will trigger both watchdogs and DACKILL. The MEDM screen is updated to accommodate the changes. The screen is also modified so the reset buttons for watchdogs and DACKILL are all available on the same screen. In the middle of this work, a bug is discovered in the ModerateWD.c where setting 0 to the ramp down time would cause the WD to loop in an endless ramp down cycle. * The Guardian is updated to recognize if the payload is tripped and decide which tripped state it should go to, "TRIPPED" or "PAYLOAD_TRIPPED". So, if both tower and payload controls are on while the payload watchdog tripped, the guardian will jump to the "PAYLOAD_TRIPPED" state and shutdown payload controls only. When the WD and DACKILL are reset, the "TRIPPED" state will dump you out to the safe state where all controls are disengaged, while the "PAYLOAD_TRIPPED" state will dump you out to the "ENGAGING_IM_DAMPING" state where the tower controls are still on. * VIS monitor is updated. It will monitor the raw sensor input and actuator output and check if they are within the operation range. The indicator will turn orange when it is 50% out of range and will turn red if it is 90% out of range. The indicator for actuators will turn blue if they are not in use. The limits of the operating range can be set in userapps/vis/k1/guardian/VIS_DICT.py. The range for OL_PIT and OL_YAW are default to be [-1,1], the lower limit of the OL_SUMs are default to be 1000 counts while those for the other are default to be [-32768,32768]. |
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==== Report for week of 1/21 ==== ==== BS (top priority) ==== * Last Friday: We tuned the IP to have a lower frequency. At the begginig we measured 78mHz. * Last Friday: With Lucia, we centered the IP and diagonalized the IP. After this process we measured a resonant frequency of 40mHz. We closed the position control loop for the IP. * We checked during the weekend and the suspension was not in a healthy state. We checked the IM horizontal OSEM coil driver, and there were some cables in the wrong connectors. (Test in instead of ...) * The adapter for the cable of the F0 fishing rod was not healtly. We fixed it but it might be good to replace it. * The commissioning team steered the BS IM to reach the Y-end and then Terrence centered the oplev with this orientation (more than once). * Fujii-san and Enzo fixed old BS geophones by replacing the Preamp. * We replaced the Geophones for the recently fixed ones. * Hirata-san and Fabian secured trim masses to the keystone. * We installed GAS Filters and IM control loops * Currently Terrence and Enzo are centering the IP using the horizontal fishing rods. |
* '''If you know the range of certain sensors and actuators, you are strongly encouraged to tweak the thresholds in the file.''' Otherwise, the function of the monitor will be very limited. |
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==== SR2 (priority 2) ==== * We measured the optic height. According to the measurement it was 0.1 mm off. However, the systematic error is likely larger (laser level, position of reference). Apparently, the RM has a small amount of roll but this should be investigated further. It might just be systemaric error of the measurement. The roll of IM was adjusted to a value close to zero before the measurement. * We calibrated the F0 fishing rod stepper motor. * We raised suspension using the jacks. We rotated the jacks by 180 degrees roughly.Compensation has to happen with F0, F1 and BF. * We removed tape, writing etc on PI and PI items. * We removed the trim mass. * Terrence restored the OPLEV to the original layout with an 1.1 m collimator and calibrated the tilt sensing QPD. Expect a pitch range of +/-223 urad and a yaw range of +\-322 urad. * We centered the IP by using the jacks. L and T came good but there is a large yaw ~ 5 mrad. * We diagonalized the IP actuation matrix. We closed the position control loop for the IP. '''(This has not happened yet).''' * We installed GAS Filters and IM control loops. '''(This has not happened yet).''' |
* Fabian checked again the GAS filter control noise: * My previous calculation considered damping filters and those injected too much noise in the observation frequency band. Rolling the filters off with (high order) Butterworth filters rendered the system unstable. |
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==== SR3 (priority 2) ==== * The bouyancy correction was calculated. It's 1.3 mm. * The strategy is rasing the suspension by 1.3 mm and then moving the keystone by 1.3 mm with the fishing rod so the alignment team can work. * We measured the optic height using Terada-san's reference. The SR2 optic was at the correct height. * We raised suspension using the jacks by an amount calculated with the jack thread: M42 with 2 mm special thread. We rotated the jacks by approximately 180 degrees. * Terrence reinstalled OL LED, collimator (1.1 m) and relaigned the OL. Both QPDs were calibrated and expect a range of L: $\pm$332 $\mu m$, P: $\pm$217 $\mu rad$ and Y: $\pm$306 $\mu rad$. * OPLEV diagonalization hasn't been done but we expect minimal coupling due to the OPLEV. Strange couplings (due to the geometry of TM) are expected but no conclusive results yet. * We removed tape, writing etc on PI and PI items. * We calibrated the F0 FR against the readout of the F0 LVDT. We removed the trim masses (110 g). Then we moved the F0 keystone by 1.3 mm downwards. * We centered the IP by adjusting the height of the jacks by small amounts. Longitudinal and Transverse positions came good but there was a large yaw (-5 mrad) when the stepper motors were in mid-range. Currently the yaw is -1 mrad and the steppers are using 80% of their range already. * The F0 yaw stepper should, in principle, give plus minus 125 mrad range. We should check with a measurement how good this range is (e.g. cables being pulled, components touching, etc.) We can use the vertical laser level as an oplev or the main interferometer beam * The front of the optic was cleaned by Hirose-san with Hirata-san's help. Hirata-san and Fujii-kun released the optic. '''The IP is still locked.''' * '''F1 fishing rod is not responsive. We have to check the cables.''' * We diagonalized the IP actuation matrix. We closed the position control loop for the IP. '''(This has not happened yet).''' * We installed GAS Filters and IM control loops. '''(This has not happened yet).''' |
* I then considered DC control filters only and I was able reduce the injectetd noise to acceptable levels while keeping the loop stable. As pointed out by Shoda-san, this was the strategy devised for the Type B prototype. |
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'''Talk about problems turning on and off control systems (Terrence and Enzo)''' From Terrence: Since the PI controller was implemented, the controller keeps accumulator displacements error and converts this error to the output. One problem arose from the mismatch of the control system and the actual hardware. Because the controller output could have a much larger value than the number of counts that can be input to the coil actuators (e.g. the controller says we should input 60000 counts to the actuators but the hardware limits the number of counts), the controller will not function as designed. As a result, the PI would shift to one side (due to insufficient driving force) while the voices coils became saturated at maximum output. Additionally, because the controller is still functioning, the integrator keeps accumulating error and hence the output of the controller keeps increasing but the object is actually stuck. This makes the IP very very unstable when the actuators are saturated. | * This has only been tested in software, not in the actual system. I aim to do implement it next week. |
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'''Give status of oplevs (Terrence and Enzo).''' | * This strategy will work only if the resonant motion of the system is not excited after disabling the payload and GAS chain damping control. On the 23rd of May Terrence measured the residual motion with the control system (including IP) on and off. There was no subtantial difference between the two. I aim to take more measurements. |
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==== SRM (low priority) ==== * Hirose-san, Hirata-san and Fujji-san fixed the RM to the SS and removed the SRM for cleaning. * Terrence installed the optical breadboards on the shelfs for the OPLEV; and, assembled the beamsplitter assembly, lens assembly and the folding mirror assembly. The LED box, collimator and the fibre connected were placed on the lower breadboard and the others are placed on the upper one. Still missing steering mirror to complete a tilt setup and a lens for the length OPLEV. |
* Terrence and Fabian are currently going through the oplev diagonalization procedure and will write down the procedure. |
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==== Postponed ==== * Raise suspension 3.5 mm on jacks. * Check/improve payload alignment and IM OSEMs. Recheck optic pitch with OL as needed.\ * Adjust F0 keystone trim to give desired height and secure weights in place. * Install geophones and arc weights. * Center and tune IP. * Hook LBB and add just enough ballast to have it bouncing. * Wipe inside tank with Vectra-Alpha wipes and IPA. * Set up TILT OL. |
* Hirata-san worked in the design of the baffles for the BS. ==== Plan for the week 7/1 ==== * Terrence and Fabian will continue writing the oplev diagonalization procedure. * Fabian will install the rolled-off the DC control filters. ==== Vacation/Travel Info ==== * Terrence goes back to Hong Kong on 7/27 (sat), last day in Kamioka: 7/25 (Thurs). * Mark's final day 6/28. === Type B (Mark) === ==== Report for the week 6/17 ==== * Izum-san pointed out the SR3 oplev control loop was not able to damp resonances at 1.4 Hz and 1.2 Hz (klog [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=9290|9290]]). Terrence checked (klog [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=9299|9299]]): * He found that the optic TFs were coupled to about 10%. I assume something changed because, as far as I understand (Fabian), the oplev had been succesfully diagonalized before to less than 1% coupling. * He moved the IP and compared IP LENGTH with OPLEV LENGTH noting the the oplev was reading only 70% of the IP displacement. * In this conditions he diagonalized the oplev but failed. There was still coupling. * He introduced a factor to have the OPLEV LENGTH measurement equal to IP LENGTH measurement. * He successfully diagoinalized the oplev. * He then proceeded to checked the filter but he was unable to reduce the residual motion. Noise is the suspect. Having appropriate wind shield is recommended. * Fabian worked in rolling-off the control filters of the GAS filters. * According to klog [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=8979|8979]] the GAS filter control noise has to decrease by 5 orders of magnitude in order to meet the requirement at 10 Hz. * A Butterworth filter of order 20 with a cut-off frequency of 5 Hz seems to reduce the noise but renders the system unstable. * More work is necessary. * Fabian joined Enomoto-kun's lecture on how to align the X Fabry Perot cavity with green light. ==== Plan for the week 6/24 ==== * Terrence will work on... * Fabian will continue working in the rolling-off of the filters of the GAS filters control loops. ==== Vacation/Travel Info ==== * Terrence goes back to Hong Kong on 7/27. * Mark's final day 6/28. === Type B (Mark) === ==== Report for the week 6/10 ==== * Supporting the commisioning team. ===== BS ===== * Type B inertial damping. This means geophone diagonalization, blending filter optimizing, etc. * Optimization gives an odd looking blending filter that blends at ~120 Hz, but works fine in IP L. [[https://klog.icrr.u-tokyo.ac.jp/osl/?r=9199|9199]] * During PRMI lock, BS residual motion was too high which misaligned the beam too much from time to time and making the lock unstable. * To fix this, I improved OL windshield so I can study the residual motion of the BS. Then I copied IP L blending filter to IP T and IP Y and cranked up the IP damping and TM damping gain. This suppressed the residual motion so the requirements are met. After this, the BS was not causing any problem to the lock anymore. [[https://klog.icrr.u-tokyo.ac.jp/osl/?r=9219|9219]][[https://klog.icrr.u-tokyo.ac.jp/osl/?r=9235|9235]] === Type B (Mark) === ==== Report for the week 6/3 ==== ===== SRM Inertial Damping and Residual Motion Stuff ===== * See Klog [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=9064|9064]] * SRM IP L and T is blended at ~110 mHz (partially optimized by gradient descent, stopped after 10 iterations, then manually adjusted.) while IP Y is blended at 260 mHz (Lucia's old filter). The stability test was carried over the past weekend with inertial damping and all other stages on. The system seems stable. * To study to performance of the inertial damping, I improvised an OL windshield for SRM. * Another round of diagonalization was carried just because we have better sensitivity. * With IP LVDT damping and other controls on, the residual motion is as follows [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=9086|9086]]: RMS Displacement: || ||Requirement ||Result || ||L ||0.4 µm ||0.1076 µm || ||P ||1 µrad ||0.0569 µrad || ||Y ||1 µrad ||0.0598 µrad || RMS Velocity: || ||Requirement ||Result || ||L ||0.5 µm ||0.1014 µm/s || ||P ||/ ||0.2165 µrad/s || ||Y ||/ ||0.1776 µrad/s || * I measured the residual motion with inertial damping, inertial damping without LVDT DC, normal damping without LVDT DC. Results are pretty similar. * I modified the optimization algorithm to allow fine learning. The cost plateaued after ~300 iterations and the blending frequency was at 78.6 mHz. I tried implementing this blending filter but the system went unstable. ===== SR3 Inertial Damping ===== * The calibration, diagonalization for IP geophones was done. * I measured and fit noise floor for LVDTs and geophones. * I found that the IP geophones have a much higher noise level than those from SRM. (1 order of magnitude higher, see [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=9088|9088]]) * This explains why the optimization result of the blending filter converges much quicker than that of SRM, because the geophone noise level limits the blending frequency to be at ~ 130 mHz. * However, when the system went unstable when the blending filter was implemented. I should try a higher blending frequency or manually adjusting the blending filter to have a proper shape. === Type B (Mark) === ==== Report for the week 5/27 (written by Fabian) ==== * Shoda-san implemented the moderate watchdog: when tripping the amount of actuation will ramp down to zero smoothly. Klog entry [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=9009|9009]]. * Terrence updated the BS guardian. * Terrence designed a VIS status monitor. The font might be too small for some people. * Terrence worked on SRM inertial damping. * There is coherence between the geophones and LVDTs at 0.1 Hz. * He designed a filter with a blending frequency of 0.110 Hz. * The system seems stable. * For SR2 Fabian calculated the sensor noise fed back into the system by the control loop: entry [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=8979|8979]]. * The GAS filters' contrbution is too high. * I asked Enzo and he didn't rolled off the filters at higher frequecies. * Filter modification was assigned to Fabian. * Fabian and Yokozawa-san measured the settings of the SR3 LVDT driver. Klog entry [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=9025|9025]]. * In the weekly comissioning meeting Fabian made the commitment of writing a list of the measurements we want to do with the DRMI for Type B characterization.I will write it by next week and send it around for comnents. === Type B (Mark) === ==== Report for the week 5/20 (written by Fabian) ==== * Terrence implemented a filter for the inertial damping. See entry [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=8905|8905]]. * The highlight of the week is Terrence's measurement of the residual motion of the SR2 optic: as measured by the oplev, it does fulfill the RMS displacement and velocity requirements for lock acquisition and, partially, for the observation mode also. See the report at klog entry [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=8949|8949]]. * The integrated RMS was calculated from 5 Hz to DC because there are some peaks between 8 Hz and 10 Hz and whose origin still has to be clarified. See the report at entries [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=8918|8918]] and [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=8933|8933]]. * After Akutsu-san's suggestion Terrence improved the air shield in two rounds, including a cylindrical cover around the viewport. This reduced the noise by about a factor of 10. * He realized setting up the shield may have slightly changed something in the oplev and carried out another round of diagonalization. * He realized the H3 coil was not working. We fixed it.A cable was disconnected. * The optic residual motion in L showed a large peaks close to 0.2 Hz, which is where the micro-seismic may become apparent. The peak was not seen in P or Y. The inertial damping system is likely not working in a suitable way. The blending frequency is 0.190 Hz which may not be low enough. * At the end measurement of the residual motion reported was carried out with inertial damping only in yaw. * Fabian, Terrence and Fujii-kun measured the settings of the SR2, BS LVDT drivers and one of SR2's. See klogs [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=8941|8941]] , [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=8951|8951]] and [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=8952|8952]]. * Fabian worked more on the calculation of the amount of sensor noise injected: * I imported Panwei's OSEM noise measurements and calculated the virtual sensor noise. * I imported Fujii-kun's measuement of the geophone noise and calculated the virtual sensor noise. * I imported the blending filter * I wrote lots of comments in Sekiguchi-kun's Matlab scripts. * I will write a klog soon with preliminar results. * Fabian submitted and abstract for the Autumn JPS meeting on September. ==== Plan for the week 5/25 ==== * Terrence will work in the optimization of the inertial damping. * Fabian will continue with the calculation and prepare a presentation for the conference in Brazil. ==== Report for Golden Week ==== * Mark monitored vent and pumpdown, and worked on vistools.py. ==== Report for the week of 5/6 ==== * Lucia and Terrence got the blending working for the IP LVDTs and geophones. * Terrence and Mark modified the models and MEDM screens to add a new IP block, IDAMP, for damping using the blended signal with inertial information, and a new DAMPMODE block for ramping smoothly between IDAMP and the old DAMP. * Mark worked on vistools.py, improving the support for cdsMuxMatrix blocks (e.g., OSEM2EUL) and adding support for cdsRampMuxMatrix blocks (e.g., the newly introduced DAMPMODE). He also created two sets of unit tests, unittest.py and unittest.sh, for the two modes of use (as a Python module in other Python programs, and as a command-line utility in bash). ==== Report for week of 5/13 ==== * Terrence measured Q's for nearly all modes on SR2 from TFs and then did some ring-down tests to get a better estimate of some high-Q modes. * Terrence and Mark looked at the velocity and angular velocity noise of the SR2 as reported by the LEN and TILT OLs. * The Y signal was fairly clean and the Y RMS angular velocity requirement was met. However the L signal was quite noisy, and was also contaminating the P signal due to the large cross terms in the diagonalization matrix. The RMS L from 5 Hz down with damping on was around 10 µm/s, which is 10 times the requirement. However little of this was due to pendulum resonances - most of the noise was featureless and broadband. In displacement units the noise was flat up to about 1 Hz and then smoothly rolled off to f^-2. The noise in the raw P and Y signals (not yet divided by the sum) was about 10 times the noise in the SUM. * We tried improving the noise with different whitening settings. Increasing the overall gain, increasing it at the QPD but reducing it at the whitening filter, and switching off the 1-10Hz boost whitening filter (and compensating software filter) had no effect. Blocking the beam reduced the noise by about 2 orders and brought the raw P and Y in line with the SUM, suggesting that the problem was before the QPD. Akutsu-san says the noise spectrum looks like it may be limited by air currents, and we probably need better wind shielding. * Mark swapped in an improved version of `vistools.py`, debugged a few small issues, and simplified the `TYPEB.py` Guardian. * Fabian embarked on a project to calculate the residual motion within KAGRA's observation band (beginning at 10 Hz) to make sure The Type B suspension fulfills the requirement, and calculate the speed of the optic to make sure we can acquire the lock. * He modified Takanori's Simulink/Matlab simulation in order to include the length sensing oplev and its control feedback path. * He imported Enzo's IM/GAS/IP-LVDT filters into the simulation. * He imported into the simulation the measured LVDT floor noise (sensitivities). * He calculated the IP-L, IP-T and IP-Y sensitivities. ==== Plan for week of 5/20 ==== * Mark at Mitaka Mon, Tue; US from Wed till 6/11. * Fabian * Import Panwei's OSEM sensitivity measurements and calculate the sensitivity of the virtual IM sensors. * Import geophones sensitivities and calculate the sensitivity of the corresponding virtual sensors. * Import Licia's and Terrence's inertial sensing filters. * Terrence * Try to reduce the OL noise and get better estimates of the RMS velocity with damping on. ==== Vacation/Travel Info ==== * Terrence's next visit from 4/18 to 7/27. * Mark's final day 6/28. |
Scraps of text for incorporation in the VIS Meeting Minutes
KAGRA/Subgroups/VIS/MeetingNAOJ
Type B (Mark)
Report for the week 6/24 (Written by Terrence and Fabian)
- Type B watchdog/DACKILL is split for tower and payload. Now, tripping the payload watchdog will only trigger the payload DACKILL while tripping the tower watchdog will trigger both watchdogs and DACKILL. The MEDM screen is updated to accommodate the changes. The screen is also modified so the reset buttons for watchdogs and DACKILL are all available on the same screen. In the middle of this work, a bug is discovered in the ModerateWD.c where setting 0 to the ramp down time would cause the WD to loop in an endless ramp down cycle.
- The Guardian is updated to recognize if the payload is tripped and decide which tripped state it should go to, "TRIPPED" or "PAYLOAD_TRIPPED". So, if both tower and payload controls are on while the payload watchdog tripped, the guardian will jump to the "PAYLOAD_TRIPPED" state and shutdown payload controls only. When the WD and DACKILL are reset, the "TRIPPED" state will dump you out to the safe state where all controls are disengaged, while the "PAYLOAD_TRIPPED" state will dump you out to the "ENGAGING_IM_DAMPING" state where the tower controls are still on.
- VIS monitor is updated. It will monitor the raw sensor input and actuator output and check if they are within the operation range. The indicator will turn orange when it is 50% out of range and will turn red if it is 90% out of range. The indicator for actuators will turn blue if they are not in use. The limits of the operating range can be set in userapps/vis/k1/guardian/VIS_DICT.py. The range for OL_PIT and OL_YAW are default to be [-1,1], the lower limit of the OL_SUMs are default to be 1000 counts while those for the other are default to be [-32768,32768].
If you know the range of certain sensors and actuators, you are strongly encouraged to tweak the thresholds in the file. Otherwise, the function of the monitor will be very limited.
- Fabian checked again the GAS filter control noise:
- My previous calculation considered damping filters and those injected too much noise in the observation frequency band. Rolling the filters off with (high order) Butterworth filters rendered the system unstable.
- I then considered DC control filters only and I was able reduce the injectetd noise to acceptable levels while keeping the loop stable. As pointed out by Shoda-san, this was the strategy devised for the Type B prototype.
- This has only been tested in software, not in the actual system. I aim to do implement it next week.
- This strategy will work only if the resonant motion of the system is not excited after disabling the payload and GAS chain damping control. On the 23rd of May Terrence measured the residual motion with the control system (including IP) on and off. There was no subtantial difference between the two. I aim to take more measurements.
- Terrence and Fabian are currently going through the oplev diagonalization procedure and will write down the procedure.
- Hirata-san worked in the design of the baffles for the BS.
Plan for the week 7/1
- Terrence and Fabian will continue writing the oplev diagonalization procedure.
- Fabian will install the rolled-off the DC control filters.
Vacation/Travel Info
- Terrence goes back to Hong Kong on 7/27 (sat), last day in Kamioka: 7/25 (Thurs).
- Mark's final day 6/28.
Type B (Mark)
Report for the week 6/17
Izum-san pointed out the SR3 oplev control loop was not able to damp resonances at 1.4 Hz and 1.2 Hz (klog 9290). Terrence checked (klog 9299):
- He found that the optic TFs were coupled to about 10%. I assume something changed because, as far as I understand (Fabian), the oplev had been succesfully diagonalized before to less than 1% coupling.
- He moved the IP and compared IP LENGTH with OPLEV LENGTH noting the the oplev was reading only 70% of the IP displacement.
- In this conditions he diagonalized the oplev but failed. There was still coupling.
- He introduced a factor to have the OPLEV LENGTH measurement equal to IP LENGTH measurement.
- He successfully diagoinalized the oplev.
- He then proceeded to checked the filter but he was unable to reduce the residual motion. Noise is the suspect. Having appropriate wind shield is recommended.
- Fabian worked in rolling-off the control filters of the GAS filters.
According to klog 8979 the GAS filter control noise has to decrease by 5 orders of magnitude in order to meet the requirement at 10 Hz.
- A Butterworth filter of order 20 with a cut-off frequency of 5 Hz seems to reduce the noise but renders the system unstable.
- More work is necessary.
- Fabian joined Enomoto-kun's lecture on how to align the X Fabry Perot cavity with green light.
Plan for the week 6/24
- Terrence will work on...
- Fabian will continue working in the rolling-off of the filters of the GAS filters control loops.
Vacation/Travel Info
- Terrence goes back to Hong Kong on 7/27.
- Mark's final day 6/28.
Type B (Mark)
Report for the week 6/10
- Supporting the commisioning team.
BS
- Type B inertial damping. This means geophone diagonalization, blending filter optimizing, etc.
Optimization gives an odd looking blending filter that blends at ~120 Hz, but works fine in IP L. 9199
- During PRMI lock, BS residual motion was too high which misaligned the beam too much from time to time and making the lock unstable.
To fix this, I improved OL windshield so I can study the residual motion of the BS. Then I copied IP L blending filter to IP T and IP Y and cranked up the IP damping and TM damping gain. This suppressed the residual motion so the requirements are met. After this, the BS was not causing any problem to the lock anymore. 92199235
Type B (Mark)
Report for the week 6/3
SRM Inertial Damping and Residual Motion Stuff
See Klog 9064
- SRM IP L and T is blended at ~110 mHz (partially optimized by gradient descent, stopped after 10 iterations, then manually adjusted.) while IP Y is blended at 260 mHz (Lucia's old filter). The stability test was carried over the past weekend with inertial damping and all other stages on. The system seems stable.
- To study to performance of the inertial damping, I improvised an OL windshield for SRM.
- Another round of diagonalization was carried just because we have better sensitivity.
With IP LVDT damping and other controls on, the residual motion is as follows 9086:
RMS Displacement:
|
Requirement |
Result |
L |
0.4 µm |
0.1076 µm |
P |
1 µrad |
0.0569 µrad |
Y |
1 µrad |
0.0598 µrad |
RMS Velocity:
|
Requirement |
Result |
L |
0.5 µm |
0.1014 µm/s |
P |
/ |
0.2165 µrad/s |
Y |
/ |
0.1776 µrad/s |
- I measured the residual motion with inertial damping, inertial damping without LVDT DC, normal damping without LVDT DC. Results are pretty similar.
- I modified the optimization algorithm to allow fine learning. The cost plateaued after ~300 iterations and the blending frequency was at 78.6 mHz. I tried implementing this blending filter but the system went unstable.
SR3 Inertial Damping
- The calibration, diagonalization for IP geophones was done.
- I measured and fit noise floor for LVDTs and geophones.
I found that the IP geophones have a much higher noise level than those from SRM. (1 order of magnitude higher, see 9088)
- This explains why the optimization result of the blending filter converges much quicker than that of SRM, because the geophone noise level limits the blending frequency to be at ~ 130 mHz.
- However, when the system went unstable when the blending filter was implemented. I should try a higher blending frequency or manually adjusting the blending filter to have a proper shape.
Type B (Mark)
Report for the week 5/27 (written by Fabian)
Shoda-san implemented the moderate watchdog: when tripping the amount of actuation will ramp down to zero smoothly. Klog entry 9009.
- Terrence updated the BS guardian.
- Terrence designed a VIS status monitor. The font might be too small for some people.
- Terrence worked on SRM inertial damping.
- There is coherence between the geophones and LVDTs at 0.1 Hz.
- He designed a filter with a blending frequency of 0.110 Hz.
- The system seems stable.
For SR2 Fabian calculated the sensor noise fed back into the system by the control loop: entry 8979.
- The GAS filters' contrbution is too high.
- I asked Enzo and he didn't rolled off the filters at higher frequecies.
- Filter modification was assigned to Fabian.
Fabian and Yokozawa-san measured the settings of the SR3 LVDT driver. Klog entry 9025.
- In the weekly comissioning meeting Fabian made the commitment of writing a list of the measurements we want to do with the DRMI for Type B characterization.I will write it by next week and send it around for comnents.
Type B (Mark)
Report for the week 5/20 (written by Fabian)
Terrence implemented a filter for the inertial damping. See entry 8905.
The highlight of the week is Terrence's measurement of the residual motion of the SR2 optic: as measured by the oplev, it does fulfill the RMS displacement and velocity requirements for lock acquisition and, partially, for the observation mode also. See the report at klog entry 8949.
The integrated RMS was calculated from 5 Hz to DC because there are some peaks between 8 Hz and 10 Hz and whose origin still has to be clarified. See the report at entries 8918 and 8933.
- After Akutsu-san's suggestion Terrence improved the air shield in two rounds, including a cylindrical cover around the viewport. This reduced the noise by about a factor of 10.
- He realized setting up the shield may have slightly changed something in the oplev and carried out another round of diagonalization.
- He realized the H3 coil was not working. We fixed it.A cable was disconnected.
- The optic residual motion in L showed a large peaks close to 0.2 Hz, which is where the micro-seismic may become apparent. The peak was not seen in P or Y. The inertial damping system is likely not working in a suitable way. The blending frequency is 0.190 Hz which may not be low enough.
- At the end measurement of the residual motion reported was carried out with inertial damping only in yaw.
Fabian, Terrence and Fujii-kun measured the settings of the SR2, BS LVDT drivers and one of SR2's. See klogs 8941 , 8951 and 8952.
- Fabian worked more on the calculation of the amount of sensor noise injected:
- I imported Panwei's OSEM noise measurements and calculated the virtual sensor noise.
- I imported Fujii-kun's measuement of the geophone noise and calculated the virtual sensor noise.
- I imported the blending filter
- I wrote lots of comments in Sekiguchi-kun's Matlab scripts.
- I will write a klog soon with preliminar results.
- Fabian submitted and abstract for the Autumn JPS meeting on September.
Plan for the week 5/25
- Terrence will work in the optimization of the inertial damping.
- Fabian will continue with the calculation and prepare a presentation for the conference in Brazil.
Report for Golden Week
- Mark monitored vent and pumpdown, and worked on vistools.py.
Report for the week of 5/6
- Lucia and Terrence got the blending working for the IP LVDTs and geophones.
- Terrence and Mark modified the models and MEDM screens to add a new IP block, IDAMP, for damping using the blended signal with inertial information, and a new DAMPMODE block for ramping smoothly between IDAMP and the old DAMP.
- Mark worked on vistools.py, improving the support for cdsMuxMatrix blocks (e.g., OSEM2EUL) and adding support for cdsRampMuxMatrix blocks (e.g., the newly introduced DAMPMODE). He also created two sets of unit tests, unittest.py and unittest.sh, for the two modes of use (as a Python module in other Python programs, and as a command-line utility in bash).
Report for week of 5/13
- Terrence measured Q's for nearly all modes on SR2 from TFs and then did some ring-down tests to get a better estimate of some high-Q modes.
- Terrence and Mark looked at the velocity and angular velocity noise of the SR2 as reported by the LEN and TILT OLs.
- The Y signal was fairly clean and the Y RMS angular velocity requirement was met. However the L signal was quite noisy, and was also contaminating the P signal due to the large cross terms in the diagonalization matrix. The RMS L from 5 Hz down with damping on was around 10 µm/s, which is 10 times the requirement. However little of this was due to pendulum resonances - most of the noise was featureless and broadband. In displacement units the noise was flat up to about 1 Hz and then smoothly rolled off to f^-2. The noise in the raw P and Y signals (not yet divided by the sum) was about 10 times the noise in the SUM.
- We tried improving the noise with different whitening settings. Increasing the overall gain, increasing it at the QPD but reducing it at the whitening filter, and switching off the 1-10Hz boost whitening filter (and compensating software filter) had no effect. Blocking the beam reduced the noise by about 2 orders and brought the raw P and Y in line with the SUM, suggesting that the problem was before the QPD. Akutsu-san says the noise spectrum looks like it may be limited by air currents, and we probably need better wind shielding.
Mark swapped in an improved version of vistools.py, debugged a few small issues, and simplified the TYPEB.py Guardian.
- Fabian embarked on a project to calculate the residual motion within KAGRA's observation band (beginning at 10 Hz) to make sure The Type B suspension fulfills the requirement, and calculate the speed of the optic to make sure we can acquire the lock.
- He modified Takanori's Simulink/Matlab simulation in order to include the length sensing oplev and its control feedback path.
- He imported Enzo's IM/GAS/IP-LVDT filters into the simulation.
- He imported into the simulation the measured LVDT floor noise (sensitivities).
- He calculated the IP-L, IP-T and IP-Y sensitivities.
Plan for week of 5/20
- Mark at Mitaka Mon, Tue; US from Wed till 6/11.
- Fabian
- Import Panwei's OSEM sensitivity measurements and calculate the sensitivity of the virtual IM sensors.
- Import geophones sensitivities and calculate the sensitivity of the corresponding virtual sensors.
- Import Licia's and Terrence's inertial sensing filters.
- Terrence
- Try to reduce the OL noise and get better estimates of the RMS velocity with damping on.
Vacation/Travel Info
- Terrence's next visit from 4/18 to 7/27.
- Mark's final day 6/28.