Departmental Bulletin Paper グリーンアスパラガス電動収穫ハサミの長さが作業姿勢へ及ぼす影響

菊池, 豊  ,  坂本, 隆行  ,  越智, 資泰  ,  田中, 亨  ,  小林, 恭

(1)  , pp.35 - 41 , 2018-03 , 国立研究開発法人 農業・食品産業技術総合研究機構 , National Agriculture and Food Research Organization (NARO)
グリーンアスパラガスの収穫作業では,しゃがみや中腰姿勢を取ることが多く,収穫期間が6ヶ月にもわたるためひざや腰等の負担が著しい。それゆえ,身体負担が少ない収穫作業を可能とするため,立ち姿勢で作業できる長い柄を有する電動収穫ハサミを開発した。その基本形の決定後に,本収穫ハサミの柄の適正な長さを明らかにするために,室内実験で柄の長さを8種類変えて模擬作業を行い,被験者の体幹傾斜を測定するとともに動作を観察した。柄の長さと被験者身長との比率が 0.3~0.4 程度の時に,体幹傾斜角度が 20゜以下で,被験者が収穫の際に隣接するアスパラガスを回避する無駄な動作を少なくできることが分かった。ほ場実験で慣行法と試作機による作業を比較した結果,作業姿勢は中腰から立位に改善され,体幹傾斜角度 20゜以上の割合が 95%から6%まで減少した。作業能率は同程度で,心拍数から見た身体負担も軽減された。In the conventional harvesting work of green asparagus spears lasts as long as six months. Workers are obliged to have crouching or half sitting postures, which results in significant burden to the knees or the back. In order to realize a harvesting work with less physical burden, we developed an electric powered scissors with a long shaft. To clarify an appropriate length of the shaft, upon fixing the basic form we performed simulation works with eight different lengths of the shaft in the laboratory test, measuring and observing trunk inclination of the subject and his or her behaviors. We as a result found that when the ratio of the shaft length to the height of the subject is about 0.3 to 0.4, the trunk inclination shall be controlled below 20 degrees, which helps the reduction of unnecessary behaviors to avoid the adjacent asparagus stems. In the field tests for the harvesting works in both conventional method and by use of the prototype machinery, we found an improvement of posture from half sitting to standing, ratio of trunk inclination exceeding 20 degrees decreased from 95% to 6% only, while maintaining the work efficiency about the same level and with less physical burden based on the measurement of the heart rate.

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