Simultaneous measurement of whole-body vibration and posture

Status:

completed 07/2007

Aims:

Epidemiological studies have shown that both exposure to whole-body vibration and unfavourable body posture may lead to health complaints and possibly impairments. No information is available on the extent to which the two forms of exposure in combination lead to health complaints or impairments. In the past, it was not possible to measure the two forms of exposure simultaneously with reasonable effort, for technical reasons. The objective of this project was therefore to synchronize existing methods for measurement and analysis of whole-body vibration and body posture. Following further development, the CUELA body-posture measurement system was used for this purpose together with a proven measurement chain for whole-body vibration.

Activities/Methods:

The body-posture measurement system already employed at the BG Institute for Occupational Safety and Health (BGIA) was limited in its scope for the measurement of body posture in a seated position, including rotation of the upper body and head with the upper body resting against the seat backrest. For this reason, the sensor system required modification, in order for the sensor to be installed at a lower height in the back area. For this purpose, new sensors had to be studied with regard to their serviceability under the influence of external interference, and integrated into the existing system. In addition, the mutually independent measurement and analysis systems for whole-body vibration and posture were to be synchronized, and suitable means developed for output of the results.

Results:

The existing CUELA body posture measurement system is based upon a scanning frequency of 50 Hz. This is not sufficient for the collection and analysis of vibration measurement results, for which a minimum scanning frequency of 480 Hz is desirable. The problem was resolved by retention of the two measurement systems in parallel and the use of a trigger signal for their synchronization. The existing CUELA analysis system, WIDAAN, was extended to permit integration of the vibration data. Because standards and directives in their current form do not permit an unambiguous, objective analysis of the results of posture measurements, a qualitative three-class "traffic-light" (red/yellow/green) classification system was implemented. The same classification system was applied to the results of whole-body vibration measurement. Data of the two types are divided into classes and related to each other on a case-by-case basis. The overall assessment is produced from the relative classification of the posture and vibration data. The method was trialled using in-plant measurement data. The objective of the project was attained, namely that of producing an integral measurement system for the simultaneous acquisition of posture and vibration data.

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