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Human vibration is a measurement of effect of vibrations to human body. Especially at work places exposed to vibrations there is a big likelihood of permanent damage to some parts of the human body. One effect is known as Raynaud's disease or the effect of white fingers where the fingers change color to white and become painful. Another typical effect of working with heavy machinery or vehicles (a typical example is the helicopter) is the problems with the lumbar region.
The human vibration module provides measurements to be able to judge the risk of such damage. It is based on an ISO 2631-1 (dated in 1997) standard which defines basic procedures, ISO 8041 (dated 2005), which defines exact procedures for measurements and ISO 2631-5 (dated 2005) which defines calculations of lumbar spine response to the vibrations.
There are two main types of measurements: whole body and hand arm. Both measurements are performed with triaxial accelerometers (it is very common to use 50 g sensors) and using special adapters. For work places with high vibrations (for example impact hammers) it is necessary to use high g sensors (500 g or more). This sensor should also survive high shock.
For the measurement we need several ICP channels with a 24 bit sigma-delta AD card (Orion1624 or DSA41, for example).
Whole body measurements
Whole body vibrations are measured with the help of the so called seat sensor, where we need to install the triaxial sensor in the rubber adapter on which we sit. It is important that the z axis is in a vertical direction, since it is weighted differently than x and y. |
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Hand arm measurements
The second application is the measurement of hand-arm where the sensors are installed on special adapters for holding them on a handle or between fingers. The orientation of the sensor is not important in this case since all three axes have the same weighting.
In theory, we would need to measure a full working day with all the significant loads. Often the measurement interval is shorter, but we need to ensure that all the significant vibration patterns are covered correctly in the obtained measurements.
