Wednesday, December 31, 2008

Finished making the BOM for the entire fast GVT system. speced out enough frame components for a fighter jet sized aircraft.

Wrote some of the Mirage Systems report.

Tuesday, December 30, 2008

Finished BOM for PCBs. Got prices for all components and checked with paul about what kind of capacitor the big one was. It was Panasonic 250V 10uF polyester film capacitor. He said that we could use a Tantilum capacitor instead, it would be smaller and cheaper. He specked one out; part # 478-1841-ND.

Checked what the longest pipe length would be that would yield a natural frequency of >10Hz, when a 2lb mass is located at the middle.
For pinned pinned BC, the longest could be 125".
For clamped clamped BC, the longest could be ~186".

Talked over tube length issues with Bryce. Concluded that we should just order the 2" OD tube. I ordered it from Tube Service. They only have 12' sections rather than 20' sections which could be a problem. They do have 6063-T6 in 20' sections but 6063 has lower ultimate shear stress.

Assigned part numbers to all the parts/drawings I created for the Fast GVT.

Monday, December 29, 2008

Talked to Brian Plasky from Mirage Systems. He said that no errors occurred during the two flights. Despite this, he said to go ahead and write up a report that discussed the vibration environment and what we (CSA) are worried about as far as vibration levels go. Also, he said it would be good to recommend a vibration mount or a different mounting orientation.

Worked on Fast GVT interface box. Measured and finalized dimensions for the laser display mounting plate and accel connector mounting plate. Made drawings for both parts.
Created BOM for PCB.

Monday, December 22, 2008

Found out today that the data from some seismic accels I calibrated was erroneous. The problem was that I used a reference accel that was not good down to the low frequencies that the seismic accels were good to. Thus, the ref accel rolled off and the seismic accels did not, causing an increase in the FRF at low frequencies. "THIS SHOULD HAVE BEEN A RED FLAG"!! Make sure it is in the future!!!!!! I needed to either use an accel that was rated to low freqs or use a coupler with a very low frequency high pass filter.

Also, I found out that an excel spreadsheet I wrote to calculate the natural frequency of a tube or pipe was incorrect. The problem is that E, the elastic modulus, is in lbf/in2, while the specific weight, rho, was in lbm/in3. I needed to convert from lbm to lbf in order for the units to work out. Once I did, I got the correct answer. ALWAYS MAKE SURE UNITS CHECK OUT!!!! I didn't do this the first time so I didnt catch this mistake until now!!!!!!!!!!

Tuesday, December 9, 2008

Worked a lot with Solid Works for the Fast GVT. For awhile I was having problems creating drawings from parts. I found out that this was because I had saved the drawing template in "edit sheet format" mode. I changed the drawing template to be in "edit sheet" mode and it was much easier to create the drawing.

Started to use CosmosWorks to redesign a flexture for a proposal.

Tuesday, November 25, 2008

Wrote the procedure for gain tuning the inertial referencing circuit.

Calibrated the LVDT for the 10" hydraulic shaker.

Tried to get some shock data from jeff to send to Loral. Couldn't figure out which files to send. I called jeff to ask but he didn't answer

Sent KD-2300 back to Kaman because they didn't fix it the first time.

Friday, November 21, 2008

Company meeting was today.

Tested more WISE isolators.

Helped Scott P. set up a DCS test to test a damper he is going to be using.

Thursday, November 20, 2008

Tested the life unit for World View. We were out of LN so I had to run to Madco to get a small 35L Liquid Nitrogen tank. The results of the test were a little different than the previous test done in August. At higher frequencies, the loss factor dropped lower. Scott P. talked to Connor and Paul about this and they suggested realigning and making sure the setup was exactly the same as last time. They also suggested testing an undamped specimen and comparing to before.
I checked the pictures of the setup from last time and discovered that there was a washer that I was using that wasn't there before. I redid the setup and retested the isolator. The results came out exactly the same.

I also tested about 5 more WISE isolators. I am now lubing the bolts with Braycote and changing them every other isolator.

Tuesday, November 18, 2008

Finished up presentation for Fast GVT progress report.

Retested WISE isolators that had come in slightly under spec. The first one, SN018, retested fine. Upon mounting the second one, SN036, one of the bolts galled which pretty much ruined the isolator. This probably happened because either (1) there was too much junk on the bolt from using it so much (2) the anodized coating wore off because it was used so much, or (3) last time it was mounted the thread was compromised somehow. This is being resolved. It looks like from now on though we will be using a lubricant when fastening the isolators in.

I setup the RR test back on the work plate to do one more room temperature test.

I setup the World View test rig so that I can do the life unit test in the next few days.

Monday, November 17, 2008

Started preparing for the Life Test on the World View Life Unit isolator. Since one of the kaman probe boxes was damaged that was used for WV, I had to get another set and verify that they give nominally the same results. I did and they agree to within about 1 percent.

I tore down the rejection ratio test rig that was in the Espec chamber.

I started preparing slides for the progress report on Wednesday. Brad wants them done by tomorrow early afternoon.

Thursday, November 13, 2008

DCS tested the WISE isolators most of the day.

Discussed RR with Brad and Paul. They suggested gain tuning a little differently to try and get it more accurate. They suggested turning the variable resister in 1/8th of a turn increments and taking an FFT of the differenced velocity when the input to the system was a 40Hz sine wave. Which ever position had the lowest value at 40Hz would be the best gain matched position. I did this and the resulting room temp rejection ratio when gain tuned like this was a bit better than before. Now Brad and Paul want me to retake the 100F and 32F RR measurements.

Wednesday, November 12, 2008

Went to dentist in the morning. Got to work around 9:10 and went directly into a product demonstration. Several representatives from FARO were here to show us three of their laser positioning systems. They were pretty impressive, they had a scanner which could scan an entire environment 360 degrees, a laser tracker that could map out large objects, and a laser arm which was both a probe and a laser scanner, for accurately scanning small to mid size objects.

Tested WISE, got through 5 more isolators.

Showed the diff temp RR test results to Brad, he wanted slighlty better performance at the 120F level. He had me do another test at 100F. They were better but still not quite under -30dB at .5Hz.

Tuesday, November 11, 2008

Retook different temperature rejection ratios. The problem that arose on Friday due to the condensation in the chamber was fixed by reseating all the electrical components. There must have been some bad connection as a result of water. The RR are pretty nice now.

I calibrated the 10" servohydraulic shaker.

Because of a death in Jeff's family, he will be gone all of this week meaning that I will have to do the WISE acceptance testing. I finished testing three of them today. Results look good.

Friday, November 7, 2008

I finished up the DC temperature sensitivity tests for the Measurement Specialties accels. Results look very similar to last time.

Found a connector and cable for the accelerometer for the Fast GVT. I chose a Mini DIN circular 4 pin connector, and a 22 AWG 4 conductor cable from Belden.

I started putting together a B.O.M. for the project.

I had to redo the rejection ratio test at different temperatures because I did not put the electronics in the environmental control chamber before. It was MUCH faster setting it up this time than last time.

Thursdsay, November 6, 2008

Sat in on a talk/discussion with David Smallwood, an expert on shock. Very interesting and insightful.

Ran part of the DC temp sensitivity test for the Measurement Specialties accels.

Started to look up connectors and cables for the MS accels.

Wednesday, November 5, 2008

Started building up a solid model of the interface box for the Fast GVT. Discovered that the display on the laser probe controller can detach and be panel mounted, while the actual controller can be mounted on a Din rail. I had Brad review my initial ideas and he suggested I make it more "idiot proof" and have both connectors from the accel and laser right next to each other so its hard to screw up. He also wants some way to group the pairs of cable that come off the accel/laser inertial sensor.

I also talked to Paul about it. He mentioned using Din-rail mountable terminal blocks to get power to each of the laser controller boxes.

I scoped out some power supplies for the interface box as well. Right now I am considering a 24VDC supply from Digikey prt no. Z2500-ND and two 15VDC supply from Digikey prt no. Z2475-ND.

I cleaned up the different temperature rejection ratio test I had conducted. I also partially re-setup the DC temperature sensitivity test for the 4000 class Measurement Specialties accels because I was not happy with the first test.

Tuesday, November 4, 2008

Got Rejection ratio at 120F, 32 F, and 70 F and plotted results.

Documented settings of laser displacement sensor controller

Sent 2 more accels to White Sands per Tim's request. Also helped him look up some specs for one type of accel they are dealing with.

Started to organize all my data from the past few weeks of work on the Fast GVT in order to get it up on the project server in an orderly manner, and also so I can put the data in a progress report.

Monday, November 3, 2008

Worked on getting the rejection ratio for the Fast GVT at different temperatures. This involved setting the shaker/accel/laser head up inside an environmental chamber. Brad suggested mounting everything on a large rigged mass so that it would be very stiff, thus not causing any modes in the frequency range of interest. I did this but you could still feel the vibrations on the stand, being transmitted to the laser head. This being the case, I mounted the laser head on the side of the inside of the oven. This gave a good RR.

I also talked to Paul J. about the interface box that would house all the circuitry and control boxes. He suggested using a 19" rack, and having Card Racks mounted in these 19" racks that would hold the PCBs. This way you could easily source the needed power to a group of PCBs. He also suggested that we have multiple interface boxes that could be stationed around the plane so you would not need incredibly long cables to run to the accel/laser head.

Thursday, Oct 30, 2008

Worked on getting rejection ratio with the 4000A-002 accel. I had to get the accel dynamics before the RR. When I did this, the transfer function showed a "blip" at around 95Hz. This is a problem because when I then went to take the rejection ratio (after having replaced the necessary electrical components), the RR was very bad at 95 Hz, where this blip occurs.

At around 2:00pm Leslie gave me the OK to send the Vixi analyzer to White Sands. I spent most of the rest of the day shipping this, then moving all my instrumentation over to the Ethyl analyzer to continue the RR tests.

I also shipped out the Kaman eddy current probe frequency demodulator box to get repaired.

Wednesday, October 29, 2008

Called Will Meenan at Kaman and talked about what to do with the broken KD2300. He said the only thing now is to just send it back for repair, which will cost $500.

Discussed the RR results with Brad and Paul J. Now that the 4000A accels are back we will redo the RR with those accels. First the circuit needs to modified to account for their dynamics.

I also conducted the DC temperature test on all 4 measurement specialties accelerometers. This test was done to see the deviation of sensitivity at different temperatures.

While doing the temp test I improved the GUI I made to plot DCS data. It works pretty well now, however I'm sure there are still a few kinks to work out.

Tuesday, Oct 28, 2008

Showed Brad results of rejection ratio test when tuned at 65Hz. He thought the RR was too high at the higher frequencies, and suggested I use an oscilloscope that can compute FFTs to tune the circuit. So, I input the signal in the oscilloscope and set it up to do an FFT, and put a cursor at 65Hz. I then adjusted the circuit until the amplitude of the FFT at 65Hz was at a minimum. I then retook the RR and got a great looking curve. It wasn't as good at low frequencies as the curves I had gotten before, but it was darn good at the higher frequencies.

The 4000A-002 accels arrived back from repairs today. I took a noise floor test with them and got a noise floor of 430uV. The spec says 500uV so these are working great now.

I set up a little for the temperature test on the 4000As and 4002M1s.

Talked to Will Meenan about the Kaman probes. He found out that the Kaman probes with CSAIDs 2001 and 2002 came calibrated from the factory with a +/-5V span, which is not how they typically are made. Usually they only have a +/-2.5V span. This interesting tidbit aside, he told me to try swapping the broken capacitor for the one that is in the demo electronics he sent. I did this and it still does not work.

Monday, October 27, 2008

Learned a little more about the LK-G32. It can be set up for spectral reflection or diffuse reflection. Spectral reflection is the perfect, mirror like reflection of light, where the angle the light hits the surface at is the angle it bounces off at. For Diffuse reflection, the light bounces off in a range of directions.
For diffuse reflection, the laser beam is perpendicular to the surface being measured. For specular reflection, you tilt the laser head so the beam is coming in at an angle. You also have to change the setting in the laser's controller to "mirror reflection".

Picked up some electronics for Brad from Jameco.

Dropped off car at Independence Acura to get fixed.

Worked a little bit on the frame for the Fast GVT. Ordered some pipe clamps that will hopefully work for 1" dia pipe.

Found out that the way we are calculating rejection ratio might not be correct since we scale the differenced output from the circuit.

Made slides for GVT PDR.

Replaced broken capacitor in Kaman box. Unit still does not work. Learned that the capacitor that broke was as Tantalum capacitor rather than a ceramic capacitor. Tantalum is a highly corrosion resistant element. The Tantalum capacitor that broke is also polarized, meaning it does matter which way you put it in.

Tried gain tuning inertial referencing circuit at 65Hz. The unit is very very finicky. It is hard to get it right. Also, there is some problems overlaying different frequency ranges to get a smooth rejection ratio plot. I don't know why the rejection ratio should be so different for different frequency ranges.

Wednesday, October 22, 2008

Found out today some more about the inertial referencing circuit. Paul told me that when he designed it, he did not design each part of the circuit (the disp part and the accel part) to have a gain of 2 in/s/V. He uses the gain of the last part of the circuit(which differences the signals) to do a final gain adjustment and bring it to 2in/s/V.

Also, I was having some pains doing the gain tuning. I couldn't match the gain well in order to give me a good RR. What I ended up doing was using a very small sample frequency. This cleaned up the differenced signal well enough so that I could easily tell when it was 90 degrees out of phase, which signifies that it is perfectly gain matched.

Tuesday, Oct 21, 2008

Learned a lot about the inertial referencing circuit yesterday and today. The 4th order filter used on the displacement part is to compensate for the phase change seen by the accelerometer.

Phase change of the accelerometer explained:
Even though the natural frequency of the accel is much higher than our analysis band, the phase change associated with the natural frequency is substantial enough at our analysis band that it must be accounted for. To do this, we referenced the accel against one with a much much higher natural frequency. This gave us a transfer function for the accel(FRF between circuit accel and reference accel), which you can fit a model to in Matlab using invfreqs. Paul then does some magic and creates a filter that will mimic this behavior for the displacement sensor.

Also, one of the parts of the circuit for the accel is to account for the laser sensors measurement delay. We had to switch one of the resistors in this section because the laser sensor we are using now is different then before.

Once all the circuitry was changed to account for the new sensors, I ran another RR test and got a good RR for the entire analysis band. Brad was pleased but wanted me to gain tune the circuit at 65Hz to see if we could get the high frequency part better. Gain tuning involves changing the variable resister to try and match the gains of the two velocities from the sensors. If done correctly, the gains will be identical and the only thing that will cause problems is the phase difference between the two signals.

The rest of the day I spent preparing the instrumentation to get shipped to White Sands for Leslie's test.

Thursday, Oct 16, 2008

Still sick but no sore throat. Came in to work.

Finished up repairing and cleaning long BNC cables. Had John Harmon help me put them away.

Called Jim Gooding about sending Leslie Chrezan accelerometers for her test in White Sands, NM. He said he should be able to send them to her.

Performed a cal check on one of the VTI1436 cards. You have tell IDeas to do a calibration or it wont be in cal. I ran a precision 5V signal to 8 of the channels. Before I performed the cal, channels were off by as much as 1.5%. Afterwords, they were off only by .16%.

Talked to Brad about next step for the inertial referencing system for the Fast GVT. He gave me a list of things to do. He pointed me to a very good reference book for electrics: "The Art of Electronics", by Horowitz and Hill.

I put the thermocouple cables from the Yuma M777 shock test in 2 plastic bins in storage.

Calculated what I need the resistance op amp in the displacement arm of the circuit in order for us to be able to use the full sensitivity range of the Keyence sensor.

Wednesday, Pctober 15, 2008

Woke up with a sore throat and feeling a little off. Came into work anyway.

Worked on removing tape and putting new BNC connectors onto 250' cables from Yuma. Will try to finish them tomorrow.

Started gathering test equipment for Leslie for her test in White Sands, NM. We don't have all the accels she needs so I will have to call the Albuquerque office tomorrow to see if they can help.

Did a tap test for Raman for his WISE job. Had Brad OK my work.

Wrapped up the Thermocouple cables from the Yuma test. Brad said to put them in a tub, put our initials, the job number, and date on it, and store it in the other building.

Tuesday, Oct14, 2008

Retook noise floor measurements for the inertial referencing circuit. I did this because before I was not powering the circuit properly. I was only supplying 12V when it actually takes +/- 15V. The new results give lower noise floors which is good. No harm done.

I also took another rejection ratio measurement. Still only getting about -16dB attenuation which is pretty bad.

The rest of the day Josh helped me put the 250' cables onto spools (which finally arrived after 4 weeks). This took a lot of time but we were able to get all ~33 cables done. Now they just have to be tested to make sure they are good.

Monday, October 13, 2008

Jeff found out that the VXI has not been doing its self calibration during start up. Even when he changed the vxi setup file (hpvxi.setup, calibrate_option), it still didnt seem to do it. Therefore,to do it manually, bring up the menus in IDeas (ctrl+m) and find the perform calibration option.

I called Kaman and left a message about the capacitor in the frequency demodulator. I checked the broken capacitor, it is a 1.0uF, 35V capacitor.

I called Jeff Chang at measurement specialties about the status of our 4000A accels.

I worked on the rejection ratio test for Fast GVT. The gains for the circuit (2 in/sec/Volt) are set based on the calibration factors of the sensors. Thus if the sensor's cal is different, the circuit will not perform the same. In my case, both sensors are different than the ones used to tune the gains on the circuit. The cal on the disp sensor can be changed to account for this, however the cal on the accelerometer cannot.

Brad asked me to get John Harmon to organize the BNC cables from Yuma.

Wednesday, October 08, 2008

Performed noise floor tests on inertial referencing circuit. To do this I shorted the displacement input to ground, then took the PSD of the displacement-velocity. I did the same to the accelerometer input and acceleration-velocity.
Once I had the noisefloors of the circuit and the sensors, I overlayed them on a plot. I had a difficult time understanding what calibration factor to apply to the circuit noise floors to get them into in/s. In the end the confusion came from two things. One, I was overcomplicating things…the output of each part of the circuit is in Volts. It doesn’t matter what happened to that voltage along the way, volts are volts. This new voltage was simply proportional to velocity instead of disp/acceleration now. The second thing that was confusing was the gain to apply. I thought it would have more to do with the cal factors of the sensors, but that is not so. I talked this over with Brad and the actual circuitry itself has a gain of 2 (in/s)/V for both accel velocity and disp velocity. I had no way of knowing this beforehand, which was slightly frustrating.
During this day I also edited the read_ati_file.m and read_afu_file.m. Before now, they did not have a field which contained a description of each channel, or have a field which specified the units. I used V=get(*ideas_fn file) to get a list of all the possible fields which can be written to the .mat file. I could not find one for units, so I just had the read files record what units you told it to export in.

Tuesday, Oct 7, 2008

Moved circuitry of inertial referencing for Fast GVT to a wood plank to get it off of the power unit.
Converted .ati files for Scott P. for World View
Reviewed circuit diagram for inertial referencing circuit and compared against the actual circuit to make sure it was wired up correctly. The only differences I could see between the actual circuit and the diagram were 1) for the accelerometer signal conditioning, pins 1 and 8 are supposed to be connected for three of the stages by a variable resistor, and are not, and 2) there is no SW2 as is shown in upper right of diagram.
Performed noise floor on new Measurement Specialties accels (4002M1-002-060 and 4002M1-005-060). Tried using another, lower noise floor accelerometer to glue back to back with the test accel. Found out that some of the ICP sensors are very temperature sensitive. Just temperature deviations in the lab will cause the signal to wander a little. Also, just holding the accel for a little bit will cause serious drift to the signal. Lesson learned!
I am still unclear about what to do about the two resulting random signals. If you add two random signals, what is the resulting signal? Is it’s RMS value twice that of the other two? If not, why?
I also helped scott plot some old WV tests, and convert some .afu files from a local modes test I did awhile ago.

Monday Oct 6, 2008

Spent the morning trying to shape a PSD so that we could use it to get calculate the rejection ratio of the inertial referencing systemfor the GVT SBIR over the entire band of 1-100Hz. The set up consists of gluing the test accel onto the shaker, and mounting the Keyence laser sensor so that it points at the accel. That way you are measuring the EXACT SAME motion with both sensors. The signals are then differenced in order to calculate the rejection ratio.
Tried using the hydraulic shaker at first, however this shaker causes too much vibration to be reacted back into the work plate, which would cause the laser to shake. This being the case, I switched to an electrodynamics shaker. This proved more suitable and easier to work with.
I tested several different source voltages and bandwidths. As it turned out, I needed to source a relatively high voltage from the VXI source card in order to get enough energy in at low frequencies, but then had to use a lowpass filter to filter out the higher frequencies that were also inevitably high in energy due to the high source voltage.
After this I ordered some LN for Bryce, and talked with Scott P. about synchronizing the last Kaman probe box that was used for World View. He said he would discuss it tomorrow.
Brad talked to me more about the rejection ratio test. The noise floors I had been using as a basis for my previous PSD shapes were not the right ones. You need to use the noise floor of the signals AFTER they have gone through the circuit. He outlined a new approach going forward in an email.