Keywords: Haptics , ISO 5349, Exposure to vibration

1) Introduction

The International Standard ISO 5349 gives guidelines for the risk assessment of hand transmitted vibration.
[?] The absorption of vibration energy in the human hand and arm has been claimed to correlate better with vibration injury than the currently used measurements of the frequency weighted acceleration (2, 7). The assumption is that a higher quantity of absorbed energy per unit time (power) represents an increased risk of vibration injury or reduction in comfort.
[?.] The aim of the present study, which has been reported in more detail in the International Archives of Occupational and Environmental Health, was therefore to see how the energy transmission changes along the hand and arm and to compare the energy transmission for two different kinds of vibration exposure, i.e. random and sinusoidal.

2) Methods

The transmission of absorbed energy to different parts of the hand-arm system was determined by simultaneous measurements on the contact surface of the hand and at the actual part of the hand-arm system.

3) Results

The results in Figure 1 show that most energy is transmitted to the hand, thereafter the wrist and the elbow respectively.
[?] The results show significant differences in the energy transmission between the random and sinusoidal vibration. Furthermore, an interaction between the two types of exposure and location was found.

4) Discussion

The results of this study show that the energy transmission to different parts of the hand and arm decrease with distance from the source. The absorption is, however, dependent on the nature of the exposure, i.e. random or sinusoidal vibration.

The results also show that the energy transmission is dependent on the frequency. From the transmission curve for the random vibration exposure, it could be concluded that for frequencies above 400 Hz, almost all of the energy is absorbed before the knuckle of the hand. For frequencies above 60 Hz the absorption takes place in the hand. No frequency dependence could be seen between the wrist and the elbow. The results also show an amplification of the energy transmission in the frequency area to the knuckle of the hand in the frequency area around 100 Hz. This peak in transmission is probably due to the resonant area of skin at the knuckle.