Are there non-contact vibration sensors for Arduino or PC? - Page 1
Forum section: electronics / beginners

author: engineheat
author_rank: Frequent Contributor
timestamp: February 01, 2019, 03:47:11 am
content: I need to sense vibration of an object, but I can't use accelerometers or piezo sensor because those requires touching the object, which is impractical in my application.I hope to use an optic based approach, or any other method that can sense the degree of vibration without contact. I need to be able to feed the data into an Arduino or a PC.I don't want to have to buy a big/expensive industrial type device. Size and price matters. However, I can place the sensor very close (millimeters) to the object. Any ideas?thanks

author: MavMitchell
author_rank: Contributor
timestamp: February 01, 2019, 03:59:56 am
content: Any idea of the frequency and amplitude of the vibration. Is the body metal..

author: jazper
author_rank: Regular Contributor
timestamp: February 01, 2019, 06:34:22 am
content: Frequency and amplitude matter..accelerometers on a membrane could work (think a speaker cone)A microphone could work depending on frequency.. or ultrasonics if the amplitude is high..

author: jazper
author_rank: Regular Contributor
timestamp: February 01, 2019, 06:36:56 am
content: http://www.warsash.com.au/products/vibration-measurement/LASER-DOPPLER-VIBROMETRY.phphttps://en.wikipedia.org/wiki/Laser_Doppler_vibrometerhttps://www.sciencedirect.com/science/article/pii/S0041624X97001029

author: David Hess
author_rank: Super Contributor
timestamp: February 01, 2019, 02:54:40 pm
content: Optical interferometry can be used to remotely measure vibration. Capacitance sensing could also work which means reluctance sensing is a possibility also.

author: Dundarave
author_rank: Regular Contributor
timestamp: February 02, 2019, 07:08:28 am
content: I understand that spy-types have been using a laser beam against plate glass windows for years, and demodulating the reflected light.It might be as simple as lining up an infrared LED and a receiver beside each other facing the target (so the LED and IR receiver don't see each other directly), and then sending a kHz signal via the LED and piping the IR receiver and a copy of the transmission into a differential op amp to get the difference.That would be interesting (and pretty easy) to experiment with.

author: ebastler
author_rank: Super Contributor
timestamp: February 02, 2019, 08:05:59 am
content: Microphones have been used successfully.But as others have said: The question is somewhat meaningless without indicating the frequency and amplitude range, and the properties of the vibrating object (size, mass, surface properties).

author: engineheat
author_rank: Frequent Contributor
timestamp: September 06, 2019, 07:45:03 pm
content: Okay, I tested with microphone. It didn't work well due to the ambient noise.The object that I want to measure vibration is an electric shaver. The FFT of the recorded sound shows a maximum frequency of interest of around 5khz (above which I'm not too interested).I don't think the laser doppler vibrometers would be within my budget (less than $1k).Now I'm looking into contact piezo sensors/accelerometers. Having never used them, I wonder if the force of contact between the sensor and the object is a key attribute I need to control. I'm thinking about using a magnet to attach the sensor to the object.This one here seems like something cheap and easy to experiment with:https://www.tindie.com/products/electromake/3-axis-usb-accelerometer/but it seems the max frequency is only 3000hz. Is this the sampling rate?Thanks

author: Brumby
author_rank: Unknown
timestamp: September 08, 2019, 10:41:45 am
content: Quote from: engineheat on September 06, 2019, 07:45:03 pmThe answer is in the specification:AVAILABLE COMMANDSHere is a list of commands that you can send to the accelerometer dongle. You can control the frequency of data sampling, the range of measured acceleration and stop/start streaming data. This dongle has an LED to indicate if the acceleration is measured and how fast it is measured. It also has an LED power indicator.STOP- Stops accelerometer data streaming.START- Starts accelerometer data streaming.FREQ frequency-Changes acceleration data sampling frequency.Available frequency values in hertz are: 3200, 1600, 800, 400, 200, 100, 50, 25, 12.5, 6.25, 3.13, 1.56, 0.78, 0.39, 0.2, 0.1.

author: kosine
author_rank: Regular Contributor
timestamp: September 08, 2019, 12:32:01 pm
content: Would a linear hall effect sensor work?SS49E datasheet says response time of 3us, so sampling rate would be adequate.https://sensing.honeywell.com/honeywell-sensing-ss39et-ss49e-ss59et-product-sheet-005850-3-en.pdf

author: DTJ
author_rank: Super Contributor
timestamp: September 08, 2019, 01:06:23 pm
content: Do you have a moving metal target on the shaver?Use an oscillator with a lossy coil to sense the moving metal.http://www.kamansensors.com/used to make them 20 years ago, I guess they still do.You can make one with a transistor, some caps and a coil & send the output to a CRO.

author: ddavidebor
author_rank: Super Contributor
timestamp: September 08, 2019, 01:24:20 pm
content: You can also use a doppler radar to measure vibration, there are articles about it, but it's not simple.

author: Dundarave
author_rank: Regular Contributor
timestamp: September 09, 2019, 01:24:23 am
content: If you can get within a few millimetres of the electric razor's moving blade (assuming that the blade contains steel), then perhaps a simple coil similar in design to an electric guitar pickup might be all you need.Essentially a variable-reluctance sensor, you could wind a quick-and-dirty coil around a magnetized iron nail and see what the output looks like when you hold the head of the nail (i.e. the coil perpendicular) near to the moving blade...

author: engineheat
author_rank: Frequent Contributor
timestamp: September 09, 2019, 04:47:31 am
content: Quote from: Brumby on September 08, 2019, 10:41:45 amA max data sampling freq of 3200 is not enough to sense vibration 5khz or above right? I assume an object that creates a 5khz sound is also vibrating at 5khz.

author: engineheat
author_rank: Frequent Contributor
timestamp: September 09, 2019, 04:50:56 am
content: Quote from: kosine on September 08, 2019, 12:32:01 pmI'm not familiar with hall effect sensors. How would it work for my project?thanks

author: Brumby
author_rank: Unknown
timestamp: September 09, 2019, 05:42:47 am
content: Quote from: engineheat on September 09, 2019, 04:47:31 amUsing Nyquist, a 3.2kHz sampling rate will be able to handle frequencies up to 1.6kHz - but that does not mean a 3.2kHz sampling rate won't pick upsomethingfrom a 5kHz vibration. You won't be able to reproduce the 5kHz waveform, but you might get something you could use.At this point, however, I will defer to those who can speak with more authority on such a subject.

author: ddavidebor
author_rank: Super Contributor
timestamp: September 10, 2019, 06:21:11 am
content: Quote from: engineheat on September 09, 2019, 04:50:56 amYou put a magnet somewhere, a hall sensors somewhere else in close proximity. Magnetic field varies and so does the hall sensor output that measures magnetic fields.