基于人机工程学的电动高枝杆锯研究

Research of electric pole saw based on ergonomics

【目的】在林木剪枝作业环节中,高枝杆锯作为一种高效便捷的工具降低了林业工人爬树剪枝的风险。本研究对市场上典型的电动高枝杆锯进行人机工程学评价,针对其缺陷提出了一种增加可移动手柄的改进方案,通过对比实验来证明改进方案的有效性,为同类型工具提供改进思路。【方法】可移动手柄通过改变握持点到重心的距离,调节工具本身重量对手臂及全身的疲劳负荷。实验选取17名男性操作者,收集操作原有电动高枝杆锯过程中被试人员的心率,肱二头肌和掌长肌的表面肌电信号,握持距离和主观评价结果等数据来选择改进方案。同等实验条件下,对比改进后的实验数据,确定改进效果。【结果】改进前被试人员的心率增加比均大于18%,表明人体全身疲劳负荷过大。肱二头肌和掌长肌归一化的表面肌电信号分别高于20%和30%,呈现出局部肌肉高度疲劳特征。通过配对样本t检验的方法,计算得出改进前后的心率增加比,肱二头肌和掌长肌的归一化表面肌电信号,主观评价和握持距离均有显著差异(P<0.05)。【结论】综合评价结果表明改进之后的电动高枝杆锯可以允许操作人员利用可移动手柄自由调节双手间的握持距离,从而降低手臂及全身的疲劳负荷,最终使得操作舒适性得到明显提升。改进成本控制在百元以下,提高了普遍推广的可行性。

[Objective]In the process of tree pruning,pole chain saw as an efficient and convenient tool effectively reduces the risk of climbing trees for forest workers.In this work,the ergonomic evaluation of typical electric pole saws in the market was carried out,and an improvement scheme with movable handle was proposed for its defects.The effectiveness of the modified scheme was proved by comparative experiments,which provided an improvement idea for the same type of tools.[Method]The movable handle can be used to adjust the fatigue load of the tool on the arm and the whole body by changing the distance between the holding point and the center of gravity.Seventeen males were selected to perform the experiment,during which their heart ratio,surface electromyography signals of biceps brachii and palmar longus,grip distance and subjective assessment were measured during the operation of the original electric pole saw,and to select improvements based on these data.The improvement effect was evaluated by comparing the improved experimental data with that of the control group.[Result]Before the improvement,the increase ratio of heart rate of the subjects was greater than 18%,indicating that the whole body fatigue load was too large.Besides,the normalized surface electromyographic signals of biceps brachii and palmar longus were higher than 20%and 30%,respectively,which revealed excessive local fatigue.By paired sample t test method,the increasing ratio of heart rate,the normalized surface electromyographic signals of biceps brachii and palmar longus,subjective assessment,and grip distance were significantly different before and after the improvement(P<0.05).[Conclusion]The overall evaluation results show that the modified electric pole chain which allows the operator to adjust the grip distance between the hands freely by the movable handle can effectively reduce the fatigue load of the arm and the whole body,and finally improve the operation comfort.Moreover,the additional cost of the modification is controlled below 100 CNY,which increases the feasibility of universal promotion.