Collecting Vibration Data With a USB Digital Accelerometer and an

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Collecting Vibration Data With

a USB Digital Accelerometer

and an Android Phone While

Analyzing With MATLAB

Collecting Vibration Data with a USB Digital Accelerometer and an Android Phone while

Analyzing With MATLAB

What makes the USB Digital Accelerometer

(Model 633A01) a great device for data

acquisition? Extreme portability.

Why not use a device most people already

carry around? The smart phone.

An Android phone and MATLAB make for an

easy solution to acquire data in the field and

analyze in the comfort of the office.

Since vibration measurements often occur in

hard-to-reach places, lugging a laptop to

acquire data may not be a convenient

option. Recording data directly onto a phone

and analyzing that data with a quick MATLAB program becomes an easy task with little user

interaction.

Developing a graphical user interface (GUI) in MATLAB optimized to read .WAV files with Model

633A01 calibration information was straightforward. The Android data recorder app

is optimized for use with Model 633A01. The USB Digital

Accelerometer proves how feasible data collection on

a phone has become. The phone can capture data

from Model 633A01 and analyze it via computer in a

few short steps. All that’s needed is a USB to micro

USB connector, a sensor and a phone.

The USB Audio Recorder app by Daniel Sobe and Dr.

Jordan is both free and easy to use. This app is able

to facilitate both the acquisition and exportation of

the collected data.

In this application, the user placed the sensor on an air

compressor and set up the app acquisition settings. The

sensor had a magnetic base for mounting. This is one of

many options that could be used, such as bolting or

gluing the sensor. Although a magnetic base allows

the user to collect data on metal surfaces, the trade-

off for convenience is the accuracy of the higher

frequency response.

After selecting a USB device, the app prompts for sample rate and sample resolution. The app

offers a broad spectrum of sample rates and serves as a very simple interface for a quick data

acquisition process. All sample rates are supported

by Model 633A01. The user selected 8000 Hz

deducing that the vibration would be low frequency

and 24 bits for best accuracy. Even better, the app

writes complete calibration data into the WAV file to

ensure data scaling would be problem free.

After collecting initial data, the WAV file, including the

embedded full sensor calibration along with the

measured data, was sent via email to a computer for

MATLAB analysis. All files were placed in the same

folder as the .WAV file analyzer. This is what makes the

phone method of acquisition so appealing – it’s

portable and there are many optional ways to transfer

your data.

The user then ran the WAV file through the script, ‘633A01_Data_Analyzer.m’ for analysis. The

GUI itself is also very user friendly and requires minimal input. The GUI automatically does

all scaling necessary to provide data in calibrated engineering units. The program reads

information from the WAV file,

including the scaling for engineering

units such as g’s and serial number,

and is able to display them according

to the user’s input settings. The

scaling is traceable back to

national standards.

Afterward, the user may input the

desired settings and click on

‘Select File & Analyze’ to choose the

data file. Although this requires the

user to do little for the inputs, the

GUI will still display accurate and

precise data.

The GUI extracts the calibration information embedded in the WAV file then displays the serial

number, sample rate of the data, date of calibration, the length of measurement in seconds,

sensitivities for the separate channels, average and instantaneous frequencies and magnitudes,

the average and instantaneous frequency spectra as well as the wave function. The program

immediately displays scaled data according to the sensor’s sensitivity and creates readable

graphs. The return on the investment of time is huge. Little effort was put into the data

acquisition and analytical processes that can now be repeated for numerous test situations.

The Android app makes it easy to record data with a phone instead of toting a computer around.

This is especially appealing for users taking several tests at several different sites. The luxury of

using the phone for recording is convenient and the GUI allows for a quick analysis in the

comfort of one’s own office.

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