Order Analysis Toolkit is acting peculiar

Salutations,
What we're experiencing isn't so much an error as a lack of expected behavior. The big picture is this: we want to generate Bode & Polar plots from proximity probe data recorded during the startup/shutdown of a turbine. The problem is that the data is too much to hold in memory at one time (5kHz sampling over ~15-20 minutes, but potentially much longer). There may be a flaw in the concept I used to create the software. I assumed that if I fed a chunk of data to the resampling vi and then to the order extraction vi I could take the resultant magnitude, phase, and RPM vectors and average them for the chunk of data (ideally 1 second) generating one point for the eventual magnitude and phase XY graphs. In this way, I would build a graph containing 1 point for each second of data that goes in. The assumption is that at a given RPM, the average magnitude and phase should be fairly constant.
Currently, at high RPM values the we seem to be getting answers (are they correct, not entirely certain), however at lower RPM values the data set returns the NaN issue. This could be due to a lack in points being sent into the VI's, as the RPM increases the amount of data information from the tach sensor (over the 1 second) increases. While probing the data after Labview's OAT Resample Waveform, the dr value remains constant during the NaN section, however it becomes dynamic when the data starts to show answers. This all occurs prior to entering the OAT track orders in resample signal vi.
Hence, we are uncertain if there are specific limitations to the vi's that aren't mentioned in the manual. Yes, I RTFM'd.
Thank you for your time and assistance,
E. Smith

The other analysis information is coming along spectacularly. It's just when we attempt to do Bode plots that there is a problem.
The minimum RPM is around 200. So, that is offering plenty of information. We've ensured the proper sampling by the Nyquist Theorem.
The problem exists somewhere in the basic assumptions of the OAT toolkit Vi's that have been mentioned. I'm attempting to decipher why this exists, and what the exact limitations are.
Thanks for the response,
ElSmitho

Similar Messages

I am using the Order Analysis Toolkit and want to get more information about the compensation for "Reference Signal Processing", which is scarce in the manuals, the website and the examples installed with the toolkit.

I am using the Order Analysis Toolkit and want to get more information about the compensation for "Reference Signal Processing", which is scarce in the manuals, the website and the examples installed with the toolkit.
In particular, I am analyzing the example "Even Angle Reference Signal Processing (Digital Tacho, DAQmx).vi", whose documentation I am reproducing in the following:
DESCRIPTIONS:
This VI demonstrates how to extract even angle reference signals and remove the slow-roll errors. It uses DAQmx VIs to acquire sound or vibration signals and a digital tachometer signal. This VI includes a two-step process: acquire data at low rotational speed to extract even angle reference; use the even angle reference to remove the errors in the vibration signal acquired at normal operation.
INSTRUCTIONS:
1. Run the VI.
2. On the DAQ Configurations tab, specify the sample rate, samples per channel, device and channel configurations, and tachometer channel information.
NOTE: You need to use DSA PXI-447x/PXI-446x and PXI TIO device in a PXI chassis to run this example. The DSA device must be in slot 2 of the PXI chassis.
3. Switch to Extract Even Angle Reference tab. Specify the number of samples to acquire and the # of revs in reference which determines the number of samples in even angle reference. Click Start to take a one-shot data acquisition of the vibration and tachometer signals. After the acquisition, you can see the extracted even angle references in Even Angle Reference.
4. Switch to the Remove Slow-roll Errors tab. Click Start to acquire data continuously and view the compensate results. Click Stop in this tab to stop the acquisition.
ORDER ANALYSIS VIs USED IN THIS EXAMPLE:
1. SVL Scale Voltage to EU.vi
2. OAT Digital Tacho Process.vi
3. OAT Get Even Angle Reference.vi
4. OAT Convert to Even Angle Signal.vi
5. OAT Compensate Even Angle Signal.vi
My question is: How is the synchronization produced at the time of the compensation ? How is it possible to eliminate the errors in a synchronized fashion with respect to the surface of the shaft bearing in mind that I am acquired data at a low rotation speed in order to get the "even angle reference" and then I use it to remove the errors in the vibration signal acquired at normal operation. In this application both operations are made in different acquisitions, therefore the reference of the correction signal is lost. Is it simply compensated without synchronizing ?
Our application is based on FPGA and we need to clarity those aspects before implementing the procedure.
Solved!
Go to Solution.

Hi CracKatoA.
Take a look at the link bellow:
http://forums.ni.com/ni/board/message?board.id=170&message.id=255126&requireLogin=False
Regards,
Filipe Silva

Order analysis, executable and LabVIEW 8.0 RT

Hi,
I'm facing a peculiar problem. I have a LV RT code which uses VIs from
order analysis toolkit. The program as source code works perfectly. But
when I create an RT startup application and deploy it with debugging
enabled, the application gives a broken arrow. I was able to track down
to some four VIs. All these four VIs use functions from order.dll
(like OAT Single Stage Interpolation with IC). There are no description
for the errors. I tried to build the application after installing OAT
runtime in the host PC. But that also didn'thelp. I am using OAT 2.1,
with LV RT 8.0. Hope someone knows whats going on...
Thanks in Advance
Kallis
Have a nice day!!!
LabVIEW | LabWindows/CVI | TestStand
Certified LabVIEW Architect

Hi,
Even after I changed the dll to the RT-dll, the executable is still not
running. Now when I try to connect to the remote application
(using the 'debug aplication or shared library' utility), I get a
'failed to connect to remote appliction' message. So not able to realy
know what's happening there inside RT. After this I tried to build an
application which has only one vi which calls the 'OAT convert to even
Angle Signal (1 channel) as a subVI. With this, the remote debugging
works, but again the VI will show a broken arrow. The error is with the
same old VI (OAT single stage Interpolation with IC.vi). Now I'm really running short of ideas....
Bye
Kallis
Have a nice day!!!
LabVIEW | LabWindows/CVI | TestStand
Certified LabVIEW Architect

Order Analysis when there is a significant DC offset in signal

Thanks for reading this. I am using the NI LabVIEW Order Analysis Toolkit to do order analysis of strain gage signals of a part attached to an auto engine. My goal is acquire data from a strain gaged part attached to an engine during its rampup and identify the signifcant orders in the strain signal. I am not able to understand an issue I see with my results in the Order Power Spectrum.
I measure the strain gage signals during the engine run-up using the cDAQ 9235 module (1000 to 6000 rpm in 15 seconds). I also acquire the Tachometer using NI-9402 module (counter). I then converted the strain signals to even angle signals, and did the Order Power Spectrum.
Please the resulting Order Power Spectrum shown in Fig1. What I am finding is that the DC offset in the strain signal shows up as a high amplitude peaks (red or green) in the Order Power Spectrum (Please see Fig 1) around order of 0. Because of these huge peaks around order 0, the order peaks of real interest around 2 or 3 order (blue or purple) are hard to discern in the graph.
The DC offset shows clearly in the graph of Strain vs RPM (RPM is a linear function of time), so essential this is same as Strain vs Time. The white line in Fig 2 is the DC offset. In this example, the DC offset is constant during the RPM rampup, but more often, the strain gaged part experiences both changing static strain and cyclic strain as shown in Fig 3. Here the part is undergoing increasing tensile strain, with cyclic strain overlaid on top of that.
My questions are:
Am I missing some key step here in preprocessing?
-- do I need a high pass filter to remove DC offset?
-- do I need to subtract the mean value of the signal from the time based signal before sending to Order Processing?
How does one handle signals that have a varying static strain in addition to a cyclic signal overlaid on top of the static signal? This appears to me a common scenario in strain measurements because the DUT is undergoing both varying static and dynamic stresses during an engine ramp.
Thanks for any comments or tips!

Other fun facts:
--- The Encoder solution has absolutely no connection to speed. It is all connected to crank angle.
For what we were doing that was perfect. We were looking at cylinder pressure and valve position vs. crank angle. But you have to measure speed some other way (use the encoder's INDEX output into a COUNTER channel, for example).
--- Measuring speed on a (combustion) engine is an illusion anyway. You can come up with an average speed, but the crankshaft literally slows down (that gas does not want to be compressed) and speeds up (exploding gas REALLY wants to get out). If you analyze the 512/rev signal vs. time, you can see the cylinders firing. A flywheel mitigates this, but everything is an average.
--- You're better off (speed wise) if the number of points you choose is a power of 2. You can use a FAST fourier if so.
--- The basic assumption behind Fourier analysis is that the signal you are analysing is synchronous to the block (the chunk you are analyzing), and repetitive: the next sample after the tail (element N-1) would be the head (element 0).
--- Order analysis involving windows (Hanning, Hamming, etc.) is simply an attempt to correct for the fact that you're measuring it wrong. If you take an arbitrary time-chunk of data, then your head may not match up to your tail. As far as Fourier is concerned, that is a sudden transition in the signal and will show up as energy spread through the 1st order, 2nd order, etc. It's polluting the data. Worse, it's not consistent: if the head and tail meet at 750 RPM, you have little pollution. If the head and tail are 180 out at 760 RPM, you have a large pollution. Hanning, etc. basically reduce that transition by bending the signal toward zero at the head and the tail. You then multiply the results by a fudge factor, because the window distorts the data.
--- If you record an arbitrary time-chunk of data, you don't have any phase information. You don't know if this particular order's artifact is related to the valve opening at 270 degrees, or the suction valve closing, or what. It's just not there. You can get a phase result, but it's a phase relative to the start of your block, and if that's arbitrary, then phase is useless.
--- All those issues are avoided if you take the data synchronously. Don't window it. Don't filter it, unless you have a known interfering signal way above the highest order you want.
I mentioned above that you can record as many channels as you like as long as the total scan time is < RPS / 512.
Obviously, that should be < 1 / RPS / 512 : the TIME it takes to turn the encoder one 512th of a rev. You shouldn't get too close to that limit, because the speed varies during a revolution.

How does Order Analysis measure phase lag, particularly super-sync amplitudes?

In recent testing of a high speed gear box, an 8X amplitude was observed (on the radial displacement probes) as the gear passed through a certain speed range. An NI4472 pci card and vi's written in 7 Express, w/ Order Analysis tool kit were configured with radial displacement probes and keyphasor as input signals. The behavior of the phase lag measurement is significant. If the phase lag of the 8X amplitude rolled as the gear passed through a particular speed range then this could suggest one particular problem, but if the phase lag remained constant then this could indicate a different problem. So, someone asked: How does the system measure phase lag of supersynchronous amplitudes?

See attached file for figure 1,2,3
The Phase measurement in the LabVIEW Order Analysis Toolkit uses the phase lag convention. Phase is defined as the angle difference measured from the peak of a vibration signal backward in time to the reference trigger point. This means the directions of numerically increasing angles are always set against the shaft rotation. The trigger point here is the tachometer pulses.
Figure 1 shows the relationship of the vibration signal and reference signal to zero degree phase. The shaft has a heavy spot and a keyway slot. When the keyway slot passes the tachometer, the tachometer detects a trigger pulse. The heavy spot causes the shaft to vibrate as the shaft rotates. When the heavy spot passes the proximity probe, the vibration reaches a peak. When the heavy spot passes the proximity probe and the keyway slot passes the tachometer simultaneously, the peak of the vibration does not lag or lead the reference trigger point. At this point the phase is zero degrees.
The other part of the convention dictates that 90 degrees means that the peak of vibration lags 90 degrees behind the trigger point. Figure 2 1illustrates the 90 degree phase. When the vibration signal reaches the peak, rotate the shaft backward (counter the rotation direction) until the keyway slot passes the tachometer. The number of degrees you rotate is the phase lag, or the phase value in machinery vibration measurement. Figure 2 shows the relationship of the vibration signal and reference signal to the 90 degrees phase convention.
For the 8x phase, the measurement is conducted in the similar way. The difference is that the 8x order component go 8 times faster than the trigger pulses. Figure 3 shows the 90 degree phases ( tacho pulse in rising edge) of the 8x order components. The phase measurement is still conducted through calculating the delay between the peak in the 8x vibration components and the trigger pulses and comparing the delay to one cycle of the 8x components. In figure 3, the signals between the two green grid lines are used to output one phase results.

Query for Sales Order Analysis

Dear Experts
I have written a Query for Sales Order Analysis and would like to have help on this.
The query is used for generating daily report for Sales Order on number of documents (Sales Order), total amount of sales orders and total GP of Sales Order. The query is written as below:
SELECT T0.[DocNum], SUM(T0.DocTotal) AS 'Total', SUM(T0.U_Total_GP) AS 'Total GP'
FROM ORDR T0 WHERE T0.[DocDate] =[%0] GROUP BY T0.[DocNum] ORDER BY T0.[DocNum]
where U_Total_GP is a UDF for storing the GP of each order.
After executing the query, a selection criteria of date appears and after a date is selected, the report shown information required. However, the query does not calculate column total for total amount and total GP. Although I know the total for each column can be displayed by pressing "Ctrl" + Click on the column title, it would have to be done from time to time.
Therefore, I would like to modify my query in order to calculate the column totals when executed. Are there any suggestions for this?
Thank you
Regards
Elton

Hi Elton,
Try this:
SELECT T0.[DocNum], SUM(T0.DocTotal) AS 'Total', SUM(T0.U_Total_GP) AS 'Total GP'
FROM ORDR T0 WHERE T0.[DocDate] =[%0] GROUP BY T0.[DocNum]
Union ALL
SELECT '', SUM(T0.DocTotal) AS 'Total', SUM(T0.U_Total_GP) AS 'Total GP'
FROM ORDR T0 WHERE T0.[DocDate] =[%0]
ORDER BY T0.[DocNum]
Thanks,
Gordon

With reference to contract Purchase Order Analysis report.

Hi,
I need SAP Standard " With reference to contract Purchase Order Analysis report"
Regards,
Priya.

Hi,
there is no standard report to get the PO list wrf to contracts,
but you can get through SE16 from the table EKPO, where you have to pass the contract numbers ( get through ME3L,ME3M or ME3C ) in the field KONNR,
lakshmi reddy

Query on Sales Order Analysis

Dear Experts
I have written a Query for Sales Order Analysis and would like to have help on this.
The query is used for generating daily report for Sales Order on number of documents (Sales Order), total amount of sales orders and total GP of Sales Order. The query is written as below:
SELECT T0.[DocNum], SUM(T0.DocTotal) AS 'Total', SUM(T0.U_Total_GP) AS 'Total GP'
FROM ORDR T0 WHERE T0.[DocDate] =[%0] GROUP BY T0.[DocNum]
Union ALL
SELECT '', SUM(T0.DocTotal) AS 'Total', SUM(T0.U_Total_GP) AS 'Total GP'
FROM ORDR T0 WHERE T0.[DocDate] =[%0]
After executing the query, a selection criteria of date appears and after a date is selected, the report shown information required. Everything is fine with this query except I would also like to incdude the total number of Sales Order (per day) right below the column "DocNum".
Is it possible to achieve this?
Thank You
Regards
Elton

Try this:
SELECT T0.[DocNum], SUM(T0.DocTotal) AS 'Total', SUM(T0.U_Total_GP) AS 'Total GP'
FROM ORDR T0 WHERE T0.[DocDate] =[%0] GROUP BY T0.[DocNum]
Union ALL
SELECT count(DocDate), SUM(T0.DocTotal) AS 'Total', SUM(T0.U_Total_GP) AS 'Total GP'
FROM ORDR T0 WHERE T0.[DocDate] =[%0]

Noise, Vibration & Order Analysis

Dear all,
I am currently looking for a program that can perform a noise, vibration and order analysis. I was just made aware that LabVIEW (Developer Suite, if I'm not mistaken) comes with Noise and Vibration and Order toolkits. I've read through the data sheets for both toolkits. Now, I'm wondering whether the two mentioned toolkits can perform the analysis below:
1. Vold-Kalman Order Tracking Filter
2. Modal and Structural Analysis
3. Noise Source Identification
4. Modal Test Consultant
5. Acoustic Test Consultant
6. Real time CPB Analysis
7. Rigid Balancing and Two-Plane Balancing Consultant
8. Baseband FFT Analysis
9. Signal Enhancement
10. Auxiliary Parameter Logging
11. Cepstrum Analysis, and
12. Envelope Analysis
These analysis modules can be performed by Bruel & Kjaer product. I'm trying to influence my superior that National Instrument can also achieve the same objectives. So, maybe the users out there, or NI technical experts can help me with this. If the two toolkits are insufficient to perform such tasks, but NI has other toolkits that can supplement, can you guys please mention it in your reply.
Many thanks!
Shazlan

The order analysis tools and the sound and vibration tools provide the fundamental signal analysis for most all machinery vibration functions. However, the application level such as hammer blow test (modal), balancing, and so forth are not complete solutions.
I recommend looking at the following solution, which is based on these tools and comes with a turn-key application solution....
www.vibdaq.com
Let us know what further questions you have.
Preston Johnson
Principal Sales Engineer
Condition Monitoring Systems
Vibration Analyst III - www.vibinst.org, www.mobiusinstitute.com
National Instruments
[email protected]
www.ni.com/mcm
www.ni.com/soundandvibration
www.ni.com/biganalogdata
512-683-5444

Jitter Analysis Toolkit - Time Interval Error.vi

Hi,
I am having a requirement to find the Time Interval Error. I found that functions under jitter analysis toolkit is capable of finding the TIE(Jitter). I am not sure how to use these functions for my requirement.
My requirement is: I will read the waveform data from a scope and have to process the data and find the Time Interval Error. My only input will be waveform data with jitter from a DUT.
If anybody could help me with the flow how to use the Jitter analysis function for my requirement then it would be of great help. Also, a detailed description about the Tie Interval Error.vi also will be useful.
Thanks,
Mano

If you are just Downloading to a Flat file then why dont you have logic in place for the program to dump the data read into the file to that point depending on any criteria like accounts or customer then clear the internal table and run it in the back ground.
try to use cursor to read the records from the table which will make it a bit more efficient than plain select stement.

How many revolutions of data are required for order analysis?

Hello,
I have a requirement to collect, process, and save data for several hours at a user specified sampling interval. I suspect that I will need to use the speed of the motor to determine how many revolutions of data I am collecting.
Is there a minimum number of revolutions of data required for order analysis?
Thanks,
Chris

HI Chris,
Thank you for posting on the National Instruments forum. To determine how many revolutions of data that you are collecting, you will need to use the tachometer signal that is coming off of your motor and is defined as pulses per revolutions. With this, the absolute minimum that you need is two pulses to figure out how fast your motor is spinning. With only two pulses, however, it will be very hard to determine the order information.
I think this KB will help you in figuring out what Window Length you need when doing order analysis.
How to Select the Window Length When Extracting Orders with Order Analysis
Please let me know if the knowledge base article does not contain the information that you are looking for.
Thank You,
Nick F.
Applications Engineer

Order analysis: poor representation at speed fluctuations

Dear all,
In our company we do shaft motion tests at turbochargers. One part of it is performing order analysis and there lies my problem.
Please take a look at picture 1 and 2. They show the speed curves and the corresponding waterfall-diagramms. The difference in the pictures is the type of speed rise.
Picture 1:
The speed rise is evenly and the representation of the 1 EO (Exciting Order) is very straight and linear.
Picture 2:
The speed rise until maximum speed is very unevenly. The speed goes up and down bewteen 20000 ... 25000 RPM. In result of it the representation of the 1 EO is very poor.
Do you know how to avoid such poor representation despite changes in speed?
Parameters used:
Highest frequenc to be measured: 1 kHz
Sample rate: 10kHz
# of Samples: 1k
Freqency resolution: 10 Hz
Thank you for your help.
Regards jenz
Attachments:
1.PNG ‏180 KB
2.PNG ‏122 KB

@ Ian Ren
I use a PXI-Chassis 1033 with a NI-6122. The speed signals is recorded by a counter (edge counting) and the vibration signal is recorded by two analog inputs.
I'm not sure whether I need an additional synchronization between the counter and the vibration signals (?). At present the counter and the analog inputs use the same 20 MHz Timebase and starts at the same time.
Do you think something is wrong?
@ Preston
(1) Yes, I only write the output of the orbit analysis VI to file.
It includes:
the offset correction
the transformation of the coordinate sytem of the raw data to the horizontal and vertical directions of the test setup
orbit presentation
Do you think there is too much to calculate and therefore delay in writing the data to the file? Please take a look to the block diagramm.
(2) Yes, I begin first writing data if the calculated speed value is > 0.
The speed calculation after the edge counting delivers a speed value at 400 RPM. At this point I have already vibration signals. So I avoid a time misalignment.
(3) No, at present I do not use NI Sound and Vibration Tools but I have the software. The reason is, that I can not provide real signals to test the software and my DAQ-Hardware.
(4) What do you mean with "writing a good size time waveform from the vibration signals say perhaps 10 seconds in each record"?
Jens
Attachments:
Orbit_VI.pdf ‏35 KB

Installation problems with Order Analysis Toolset

I am trying to install Order Analysis Toolset version 2.0 on my computer, but it is not allowing me. Whenever I prompt the installation, an error message appears which says "You must install LavVIEW 6.1 or higher version before running Order Analysis Toolset 2.0 Setup." I have LabVIEW 2010 already installed. Why is it giving me this message?

Hi,
Version 2.0 of the Order Analysis Toolset was released in 2003. NI does its best to maintain compatibility, but over the years compatibility with version 2.0 was likely dropped in favor of newer tools. In this case, the order analysis functions were incorporated into Sound and Vibration Measurement Suite starting with Version 5.0. If you'd like to use these functions, I'd recommend using the appropriate version of the suite for your version of LabVIEW.
http://sine.ni.com/nips/cds/view/p/lang/en/nid/203624
Regards,
Luke B.

ORDER ANALYSIS

Hi all,
I m really very confused,i need to have order analysis for that i m using the function "Call OrdATParaSet(XW, Y, X1, ) " in result i m gettinga number of channels "time,rotational speed & orders magnitudes" i am using the data available in labview examples(order analysis) while doing analysis in labview it's giving correct waveform but while doing analysis with same data files in diadem it's always giving order magnitudes=0, so what can i do for this?
thanks
Nidhi

Hi Nidhi,
This use case requires that you briefly suspend the standard VBScript error checking, like this:
On Error Resume Next
Call ChnOrdATCalc(XW, ChnNoStr1, ChnNoStr2)
ErrNum = Err.Number ErrMsg = Err.Description
ErrSrc = Err.Source On Error Goto 0 IF ErrNum <> 0 THEN MsgBox "Error " & ErrNum & ": " & ErrMsg & vbCRLF & "Occurred in " & ErrSrcEND IF
Brad Turpin
DIAdem Product Support Engineer
National Instruments

Process Orders analysis Target Cost & Quantity is showing as zero

Hi,
I am facing a very pecuilar issue.
On analysing the cost (COR3) of my Process Orders the Target Cost & Quantity is showing as zero.
However, actual costs/quantity is showing correct.
What could be the possible reasons for the same.
Thanks in advance.
Regards,
Vikrant Sood

Hi,
Are you done with Goods Receipt(GR) from production to Inventory?If GR is not done,you dont see target costs in COR3
Check standard costs of the finished material in MM02-->costing veiw2.If there is no standard costs for materials,you dont see target costs in COR3.
Hope this helps you.
Thanks,
Anusha

Order Analysis Toolkit is acting peculiar

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