Device to Hand Vibration Measurement

[ryszard]

I want to measure the vibration effect of a small handheld device upon the users hand/fingers. My question is, what should I be looking for? I expect that the human hand will react to certain specific frequencies but which are important? Or are there other techniques I can use to evaluate the effect? I would like to know what vibration characteristic would be unacceptable by the user. This will aid in the design of the device as I have some control over the source of the vibration.

 

[brad]

I don't know of a specific reference. However, several years ago I was doing some work similar to yours, and much of the research material utilized studies by the Institute for Sound and Vibration Research ("ISVR&quot. I no longer have access to the more specific details of my work (which was at a previous employer), but if I had to redo that, I would start looking at ISVR discomfort studies.
Hope this helps.
Brad

 

[GregLocock]

The draft ISO standard 5349 recommended a maximum of 7 mm/s for a single frequency input between 16 and 1000 Hz, for 4-8 hours, as an exposure limit.

At 8 Hz 14 mm/s is allowable.

If the vibration increases by 5 then the time allowable drops to less than 1/2 h per day.

Comfort limits will be 10 dB or more down on this exposure limit. Little work has been done on multi-frequency inputs, but I suggest that a vibration dose value (time average of the 4th root of the 4th power of the signal, I think) would probably be a good place to start. Cheers

Greg Locock

 

Hello ryszard,

You may wish to review an article in the July 2001 issue of Sound and Vibration magazine. The title is "Instrumentation for Measuring Coupling Forces of Hand-Held Tools. The authors are Donald Wasserman, Jack Wasserman, and Jae Ik Ahn, of the University of Tennessee, in Knoxville.

The magazine website is

http://www.SandVmag.com.

Good luck.

 

[Hatch]

The ISO Standard 5349 is the Standard I use for hand/arm vibration measurements. The details are completely described. However it can be difficult depending on your instrumentation to measure 3 axes of vibration simultaneously and apply the appropriate filetering and weighting functions at the same time.

I use the Larson Davis HMV100 human vibration meter (link below). It is versatile machine and it conforms to the ISO 5349 Standard.

http://www.larsondavis.com/

The only other item of importance is how to couple the accelerometer (usually a triaxial). There are several methods depending on the type and direction of the tool grip. I do no use them, but Larson Davis also sells several fixtures to mount the transducer for a hand held tool.