Integral of waveform graph to calculate area under curve over time

Hello ,
Please find my attached VI and please help me for integration to get area undercut for my waveform graph.
I would like to find total Energy output from my wind power waveform graph oever one month period of time.
I believe i have to integrate to get area under curve and so i m now using integral tool in labview as attached.
As I don't have expected ans for my result and so i want to make sure the tool that i m using is correct.
Please advise me which method of integration shall i use for my graph.
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Attachments:
Wind data only.vi ‏134 KB
wind data.txt ‏1253 KB

I don't know about your calculations to get the Wattage. But as far as integration, you really should supply a dt (sample rate) in order to get a proper energy measurement. I would use your second integration method (the one with "Result" as the indicator) and give it the dt as well.
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Calculate area under XY graph

Hello to all, I am plotting the data acquired from the system as amplitude v/s time on XY graph. My task is to calculate are under the graph and am using integrator tool to achieve this. However, feel that am not using correctly as answer is not matching with expected value. For example, I have plotted y=x function and as per the definition area is equal to 0.5*height*base for area under the graph. It is not matching, kindly help as I want to find out area under the curve for any two points of X-axis.
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The integration gets accurate in your case if you change the integration method to 'trapezoidal' instead of the default 'Simpson's Rule'.
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I need to calculate area under the graph, but really have no idea.
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Merci.
Solved!
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Attachments:
Graph PV.JPG ‏35 KB

I don't know whether the example CC attached in this thread will help you or not. Please go through it.
Start your own program. Whenever you stuck up at any point, post here. Genius people around the forum here will surely guide you to proceed further. don't worry.
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Message Edited by mathan on 03-16-2009 05:33 AM

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Using the trapezoid method, the numerical integration is rather direct.
See the attached vi.
You can't get the function described by the X and Y arrays. You need to know the function from start ! However, you can always fit a function to the data. Polynomial curve fitting is quite popular. Of course this is something you could have done : fit a polynomial, then integrate it. With a large number of points (such as yours), the result will not be better than the trapezoid method.
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Hi shefalika,
It looks to me like the ChnIntegrate() function is the one to use. Note that the entire area under the curve is just the last value of the integrated curve. I included your original data in the ZIP file attached below, along with a quick VBScript which loads the data, creates 2 new channels which are the integral of channels 2 and 3 vs. channel 1, respectively, and loads a REPORT layout to show the results.
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Area Under Curve = @str(ChDX(CL('Area1'), 'Area1'), 'd')@
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Area Under Curve.zip ‏12 KB

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Hi again,
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bimanual combined with metronome_conds.vi ‏174 KB

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You didn't say much about what you are doing. The CNiMath::Integrate function should be able to do this for you. Maybe you don't understand the function. You would input your waveform as a vector (say 1000 elements), then the delta time between each element (1/sampling rate), then the first and last value of the discrete integral (waveform[-1] and waveform[n]). Then, on output, the vector would contain the integrated data. You could get the sum of the elements to get the total area under the curve.
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MIN MAX A.vi ‏16 KB

Hi all,
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Solved!
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Attachments:
data points.xls ‏67 KB

Hi RSH,
Ignore the above, I wasn't thinking clearly. I banged out a quick data set and tried it out, and it turns out to be much simpler-- you just need to calculated the integral channel and look at the last value in the channel, like this:
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Hysteresis.zip ‏3 KB

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Hi,
I created an Xcontrol for a waveform graph. The datatype (under Data 1.ctl) is a WaveformGraph reference type.
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Attachments:
GraphDisplay XControl.7z ‏1717 KB
Tester.vi ‏15 KB

It looks like the XControl data is a waveform reference (strict). I can't open the XControl though, because I don't have a 7z compiler, but the problem is probably that the refnum will only take in a reference to an exact waveform graph because it's strict.
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Waveform graph x scale

Hello,
I am using a waveform graph. My x scale is the time value of data being taken.
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Please ...using a chart is NOT an option as I need cursors.
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Simply invert the wires at the build array located just before the Graph
Message Edited by JoeLabView on 06-20-2007 03:44 PM
Attachments:
buildArray.PNG ‏2 KB

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I am measuring a torque waveform that a shaft produces as it spins up to speed. I am using the waveform vi's in Labview to calculate the total time of the waveform. Is there an easy way to calculate the area under the waveform? The hope is that we wil be able to figure out the amount of work done.

Here is a VI that should do the trick. It is a basic integral of your waveform.
Christian L
NI Consulting Services
Christian Loew, CLA
Principal Systems Engineer, National Instruments
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Attachments:
waveformpicture.vi ‏80 KB

Integral of waveform graph to calculate area under curve over time

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