Motor Modulation Vibration Test

[chassan]

Hello,

1. Does anyone have any experience with collecting and analyzing motor vibration data to get the long-term modulation vibration data (or know where I can get more detailed information)?

From what I can gather, it essentially involves continously collecting data for 10-15 minutes, extracting orders (1/2X, 1X, 2X), and then recovering and graphing the amplitude modulation envelopes for each order.

2. What is the best way to collect 10-15minutes of data (at around 10kS/s)...is streaming to a TDMS file the best (only) option and then post-process it?

I greatly appreciate any information, resources, references that you might direct me to.

Thanks,

Chris     

[preston_johnson]

Thanks for your post.

I would definately use a TDMS file for streaming the data.  This makes the file very versatel for opening it in a number of places such as LabVIEW and DIAdem and even others. 

In our Sound and Vibration Measurement suite, we have the tools for tracking the orders you are interested in, including 1/2.  We also have an envelope detection algorithim and function you can use to detect and extract the envelope. 

http://zone.ni.com/devzone/cda/tut/p/id/3575

http://sine.ni.com/nips/cds/view/p/lang/en/nid/203624

Let us know what other questions you have.

[chrishassan]

Preston,

Thanks for the information.

I can't find the envelope detection vi?  Should I use the OAT Detrend Analog Tacho Signal.vi?

Thanks,

Chris

[preston_johnson]

The Envelope detection VIs are in the Sound and Vibration Measurement Suite version 6.0.  In the Sound and Vibration palette, there is a diagnostics group with envelope detection included. 

Here is an excerpt from the help files:

http://zone.ni.com/reference/en-XX/help/372416A-01/lvoat/oat_envelope_detection/

[chrishassan]

Preston,

Does this mean that envelope detection is not available in the "old-school" OAT toolkit (I think it's v2.1) where S&V and OAT were separate products?

Thanks,

Chris

[preston_johnson]

Yes, the envelope detection was added with the Sound and Measurement Suite version. 

If you are willing, an alternative method is using an hilbert transform.  I do not recall the details here, yet there has been other discussions in the forum regarding the hilbert transform for envelope.

[tnek]

Hi Chris,

Following up on what Preston recommended, you may want to check out this article. Here is a pretty cool demo of the Hilbert transform being used to detect echoes in a room.

Regards,
Kent
Applications Engineer