伐採跡地走行中のトラクタの振動とオペレータ心拍数に関するスペクトル解析

Abstract

伐採跡地を空荷で走行中のトラクタの振動とそのオペレータの心拍数をFMテレメータ方式で同時, 連続測定した。得られた各データをランダム変動をする時系列データとしてとらえ, スペクトル解析法にて解析した。前報の集材作業中の場合 (文献 1) 参照) とは異なり, 一連の手順に従った明瞭な作業サイクルを持たず, トラクタの動きが林地表面の状況などに左右され易い本事例ではトラクタ振動および心拍数の変動は共に, 全体としてみればランダム性が強く支配した。しかしその中に存っても, 二三の周波数域では両者に周期性が認められ, そこではやはり心拍数はトラクタ振動の変動にほぼ対応して変動していると推察された。

In the moving across the cut over area of a forest, the vibrational accelerations of a tractor frame and seat and the heart rate of its operator were measured continusouly with an FM teremetry system. And the dynamic response characteristics of them were searched with the spectrum analysis, in which the data obtained were interpreted as the random and digital ones (N.B. as for the spectrum analysis for the case of the tractor skidding operation, see literature 1)). As the results of analyzing the auto-and cross-correlation functions and the power spectra, the followings became clear: In this case, the travellings of a trcator had not such a certain operating cycle according to the series procedure as the case of the tractor skidding operation and were apt to considerably depend on the conditions of the surface of forest, so that both the vibrations and the heart rate changed randomly as a whole. However, in spite of the domination of such randomness, were also recognized in the changes of them some periodicity which nearly corresponded to the periods of a set of forward and backward travellings of a tractor etc., so the correlations of the heart rate with vibrations were perceived. And further, through the analyzing the frequency response functions, it was proved that there was a clear linear response between vibration of a tractor frame and its seat, but there was little linear response between vibrations and heart rate.