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Topic: Project Query (Read 489 times) previous topic - next topic

DMED

Respected Sir,

I am doing my thesis work on "Peripheral Neuropathy assessment of Diabetic patients using perception of vibration".In which i use vibration motor to produce vibration with frequency 128 Hz. now i attach a tip(pin like structure) over the vibration motor.than there will be some amount of frequecy loss at the tip of pin.so is there any formula to calculate a frequency loss using area of pin ?or any other alternative way to calculate frequency loss.Hope for positive response.Kindly inform me as soon as possible.

wvmarle

Not sure what this has to do with Arduinos... but here my take.

Frequency loss: as long as you have the pen attached firmly to the motor, and can make sure the motor continues to run at 128 Hz (you have a speed controller?) the pen will also vibrate at 128 Hz.

The frequency of vibrations on one side of the pen is always the same as on the other side of the pen.

The amplitude of the vibrations may however be very different.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

DMED

Respected Sir,

I use arduino board.and I use small coin vibration motor to produce vibration.and frequency remain constant 128 Hz. Now i  want to make some(not same as that but something like that) pin like structure attached in figure 2(b) in below link. so you get brief idea.at the tip of pin will i get vibration with frequency 128 Hz? or loss frequency ? if loss than how can we calculate that? Hope for positive response.Kindly inform me as soon as possible.

TomGeorge

Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html

Thanks.. Tom.. :)
Everything runs on smoke, let the smoke out, it stops running....

wvmarle

No link; no image.

A pin attached to a vibrating motor will vibrate at the same frequency (bar overtones).

Note that if you don't have any speed control of your motor you don't know the frequency, as the moment you attach the pin to the vibrator it is likely to slow down. Press that vibrating pin to someone's skin or so, and it's going to slow down even more.

Note that also amplitude may change, and that depends on the amplitude of the vibration the motor produces, the shape and weight of the object attached to it, and any external forces on it such as skin pressing against it.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

DMED

Respected Sir,


Sorry Sir.This is a link that i does not mentioned in above reply.Here i attached a image of mechanism that i want to do.

https://www.researchgate.net/publication/281140118_Stimulation_Actuator_for_Walking_Support_Two-Point_Threshold_on_Planta_Pedis

now you can get brief idea.and i am extremely waiting for your suggestion for the same question that above posted.


wvmarle

Thanks. Seeing the device doesn't change anything to my comments above.
1) the frequency of the tip will be the same as the frequency of the motor,
2) the frequency of the motor will depend on whether the thing can vibrate freely or its movement is impeded,
3) the amplitude will change with frequency and how it's installed and any impedance of the movement,
4) you won't have a clue of what the actual frequency is unless you measure this.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

TomGeorge

Hi,
OPs pic.


Thanks.. Tom.. :)
Everything runs on smoke, let the smoke out, it stops running....

TomGeorge

#8
Feb 17, 2018, 02:10 pm Last Edit: Feb 17, 2018, 02:13 pm by TomGeorge
Hi,
Have you got the vibration motor to vibrate at 128Hz, how have you measured it?
Do you have a link to the motor?

These motors rely on their mass as part of the vibration system, so adding some extra mass may cause some small detuning.

Keeping the added mass as low as possible will help.
With no feedback from the motor it will be hard to tell.

I think this is your motor'


Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

LesserMole

Have you got the vibration motor to vibrate at 128Hz, how have you measured it?
Do you have a link to the motor?
This topic is interesting so I did a quick search, and found some discussion on the motor and its frequency here with same OP from a month back.




TomGeorge

#10
Feb 17, 2018, 02:32 pm Last Edit: Feb 17, 2018, 02:34 pm by TomGeorge
Hi,
Thanks for the link.

As was pointed out there, without feedback you will not be able to ensure 128Hz or 128 x 60 = 7680 RPM.

An accelerometer on the motor would help, its signal would be pretty well noise free, being physically connected to the motor, the amplitude would be very high.

Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

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