A Wireless Measurement System for Estimation of Human Exposure to Vibration During the Use of Handheld Percussion Machines

摘要

This paper describes the project of a measurement system for the estimation of the hand–arm exposure to vibration due to percussion machines. The system permits checking the observance of the safety requirements for the worker health during the use of vibrating tools. Pathologies affecting the neurological and vascular systems may be possible consequences due to the frequent exposure to high levels of vibration. The attention is focused on handheld percussion machines. Consequently, the main effects concern syndromes of the bones and muscles of the hand–arm system. Thus, to prevent or reduce possible hazards for health, national laws and international regulations fix maximum tolerable levels for daily vibration exposure. In this view, the authors have projected a measurement system that is able to acquire and process the acceleration levels transmitted to the hand–arm system. The system project has been improved by using radio frequency modules. This way, noises and potential damages to the processing board have been reduced. In fact, wireless communication allows the sensor, which is worn by the workman, to transfer data and available information to a remote DSP unit operating within the covered range. As a result, the vibration affects only the sensing unit. The sensor consists of three accelerometers orthogonally displaced. According to the guidelines of the Standard ISO 5349, the DSP board has the task to remotely process the acquired data by means of embedded algorithms to estimate the daily vibration exposure value. Two memory devices store information on the workman identity and on the metrological characteristics of the measurement system, respectively. When the estimated value of vibration absorption overcomes the safety limits, an acoustic alarm and a warning message on display alert the user to stop the use of the vibrating machine. A Web page keeps track of the vibration exposure history of the worker. Further advances and experim-n-nental results concerning the system characterization have allowed the computing algorithms to be optimized. The accuracy and reliability of the system's computation have been improved to reduce possible fault occurrences. The aim of the proposed project is to provide a prevention device for assuring safe working conditions during the exposure to vibration. Therefore, the system assists the exposed workman to avoid the absorption of high levels of vibration according to the regulations.