Convert Accelerometer Data mV/g to Vibration in/sec without toolkit

[AnotherLabVIEWguy]

I have a Dytran 3211A2 accelerometer which is sending me a +/- 5 Volts signal (100 mV/g) and I want to convert that signal to vibration (in/sec) - I don't have the sound and vibration toolkit but I am hoping I can still accomplish the above with the full development LabView version that I have. I am comparing my LabView measurements with a standard off the shelf vibration transmitter Wilcoxson iT-150 (which does the above conversion with on-board circuitry) and am nowhere close - I have attached my code. Can someone please point me in the right direction or let me know if this is only possible with the vibration toolkit ? I have read numerous forums but most of them seem to be pointing to the block in the vibration toolkit. I am able to get the FFT portion of the GUI to work correctly.

[mcduff]

There are a couple options for you if I understand your post correctly.

You are integrating the time domain signal to convert the acceleration to velocity. First you scale the voltage signal to get the acceleration and then integrate. The integration is extremely sensitive to any DC offsets and low frequency components in your signal. You can try high pass filtering the signal before integration, for example make the cut-off between 1-3 Hz, or you can remove the mean of the signal before integration, You can also do both.

The other option is doing the FFT of the acceleration, then doing the integration in frequency space, which I believe is multiplying each component by j/(2 pi f). You can can the invert the FFT, but once again before the inversion set the DC component to 0.

I am assuming you have harmonic motion here.

mcduff

[AnotherLabVIEWguy]

Hello Mcduff, Thank you for the pointers! Yes, I have harmonic motion since the accelerometer is mounted on an electric motor housing.

I have tried all the suggestions you had below along with other iterations for the past few days but I am still struggling. Do you have any more pointers to guide me further ?

Thanks for your time.

[mcduff]

Can you include some data? Hard to diagnose without data.

mcduff