Are smartphone accelerometers useful for vibration characterization? 1

[mweida15]

I've found several accelerometer apps for smartphones (for example

http://www.iseismometer.com

and

http://www.now-instruments.com/products/3-vibsensor

). Are these useful for doing quantitative vibration analysis, and if not, what are their deficiencies?

 

[IRstuff]

Unless you get the outputs directly, you might not get much in the way of frequency response. Then, there is the using of not having a rigid installation to the unit under test. You know that typical accelerometers are Super-glued to the unit under test, right?

TTFN
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Of course I can. I can do anything. I can do absolutely anything. I'm an expert!

 

[DubMac]

Garbage in = garbage out

 

[Strong]

I guess you can't afford to try a Free App or make a list of your measurement requirements!!
Lazy In = Lazy Out

Walt

 

[SomptingGuy]

I quite like the free apps that stream accelerometer data into files I can easily upload to my PC. I've been using one to quantify the vertical shaking I feel at my desk when fork lifts pass by the building. I wouldn't want to try to measure anything much more severe than that.

- Steve

 

[DubMac]

For measuring something with no requirement for accuracy, this would be fun to play with.

For gathering equipment vibration data, useless. Mainly because of garbage input data.

And you know what they say....G.I.G.O.

 

[Strong]

I'll apologize in advance if my previous response was too harsh. This Forum does not appear to allow editing, and this is unfortunate. The OP stated: "Are these useful for doing quantitative vibration analysis, and if not, what are their deficiencies?"
I am constantly checking for handy and useful vibration measurement apps for my Samsung Note II (Android) phone, but nothing was useful to me so far. The internal MEMS accelerometers have very low F-max for machinery vibrations, but may be OK for low frequency structural/seismic vibrations. Another issue is mounting/attaching the phone onto a surface. Finally, I would not trust any of these apps for quantitative measurements without amplitude and frequency calibration against a known good reference. Electricpete and perhaps a few others on Forum have "played" with these apps, so perhaps they can offer 1st hand experience. Probably fun apps to use while riding a roller coaster!

Walt

 

[SomptingGuy]

Calibration:

I can't imagine anyone with the money for a calibrator would use a phone as a measurement device. I would probably accept the nominal fatory cal and worry more about frequency response (primarily of the fixture).

I'm not quite sure what is meant by frequency calibration - how would you go about fine-tuning the sampling rate of the system?

My main issue with tha apps is data streaming consistency. I've seen drop-outs in the time domain missing/skipped samples). I'm just guessing here, but I think the underlying operating system may not be up to true real-time measurements.

- Steve

 

[GregLocock]

I suspect

http://www.invensense.com/mems/gyro/documents/PS-MPU-6000A-00v3.4.pdf

is the sort of thing in a phone, as such any limitations in frequency reponse are likely due to software and OS. The hardwired upper frequency limit is 260 Hz,

You can get these on a board for about a dollar, so with a 4 dollar TFT screen and a 4 dollar arduino you could build a 6 axis rig for 20 dollars, and probably 20 hours in programming.

Cheers

Greg Locock


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[glass99]

We have successfully used an iPhone to measure the natural frequency of a structure with a frequency of approx 2.5Hz. You get a reasonably smooth sine wave which tracks analytically predicted movements relatively well. For natural frequency determination, you don't care that much about the amplitude of the acceleration, so calibration doesn't matter that much. The clock in the phone is pretty accurate.

The biggest restriction I have found is the sampling frequency. I have not managed to get more than 60Hz sampling frequency out of my phone.

The huge advantage of an iPhone is you can just duct tape it to a structure and press the record button. It is orders of magnitude less effort than traditional accelerometers.