Shaker Controller

[KowdTek]

Hello! I was asked to develop a random vibration controller base on standard test method for random vibration testing of shipping containers.  Now, I already have the PSD profile and I’d like to ask what do I need to do with this profile so I can feed it to our amplifier. Hoping that someone else here has already done this.

Thank you very much!!

[Andrew_B]

Hello KowdTek,

LabVIEW does not have a built-in function that would create a noise signal given the PSD profile. However I would encourage you to take a look at the Signal Processing palette within LabVIEW so you may be able to code the functionality yourself. Some good online examples where this topic has been discussed are at generating noise with different power spectra laws and generation of noise with a given PSD.

Please let me know if you have any related questions, as I will be happy to work with you on this issue.

Regards,

Andrew Brown

Applications Engineer

National Instruments

[KowdTek]

Hello Andrew,

First of all, thanks for taking some time to answer my post.

Since I'm really new to signal processing I guess it's safe to ask what are the necessary steps on creating noise with specific profiles just like mine. Would it be sufficient if I take the magnitude of FFT - square the FFT's magnitude - inverse FFT - take the STD dev then wire it to Gaussian Noise vi? From there I'll be able to add the build waveform and connect that signal to waveform generator.

I'm also planning to verify the signal by using accelerometer to see if its signal is similar to the profile. Do I need the SVT to do this?

Thanks again...

[Andrew_B]

Hello KowdTek,

I am unsure on the exact process you would need to use with the Signal Processing palette in order to get the noise generated with the PSD. I will look into the issue, and I should be able to give you an update in the near future.

In regards to your related question about signal verification, what specifically are you referring to with the SVT?

Regards,

Andrew Brown

[Andrew_B]

Hello KowdTek,

If you are interested in generating white noise with a Gaussian profile that matches your PSD, the method you mentioned (take the magnitude of FFT - square the FFT's magnitude - inverse FFT - take the STD dev then wire it to Gaussian Noise vi) appears to be a good method. Some additional methods of generating the noise can be found at this website and the LabVIEW Help page on Noise Generation.

Regards,

Andrew Brown 

[KowdTek]

Hi Andrew!

Thanks for all the help!!

[PFour]

Hey KowdTek,

Curious if you were able to successfully use the FFT profile to generate a waveform matching your required PSD? Would you mind posting your VI or further explanation on your process? Much appreciated! Thanks!

[KowdTek]

Hello Pfour,

Unfortunately, this project was cancelled as we decided to use UPS testing facility instead. However, I've used this vibrationdata (http://www.vibrationdata.com/software.htm) software to simulate the shipping profile.

-K

[PFour]

KowdTek,

Great! I'll take a look -- thanks for the link.

Cheers,

-PFour