Estimation method of vibration exposure assessment for mechanized handheld tools operators basing on precise detection of devices operating mode

Currently, it is obligatory to assess the employees' exposure to harmful factors.An assessment of chainsaw operators' exposure to vibration and noise should be made at the workplace (in the field or forest).A precise determination of a chainsaw operator's exposure to vibration and noise during an 8-hour work day can be based on dosimetric measurements.However, this type of measurements are difficult to be performed in the field or forest conditions.The assessment of a chainsaw operator's exposure to vibration and noise can also be made by an indirect method, based on a determination of reference vibration and noise parameters related to operation of the chainsaw in particular modes (Idle, Racing or Full Load) and estimation of time shares of individual modes of the chainsaw's operation in its total operating time.This article presents an improved device dedicated for field measurements of rotational speed of a chain sprocket and a chainsaw's engine shaft.The article also presents the principles of identifying chainsaw operating modes based on these measurements.An analysis of the angular acceleration of the chain sprocket and engine shaft was also carried out.The presented approach, in addition to the basic operating modes, enables identification of transition states, such as acceleration, deceleration or jamming of the cutting set.