A biomechanical model is presented, and combined with measurements of tip press force, to estimate total user hand force associated with two pneumatic nail gun trigger systems. The contact actuation trigger (CAT) can fire a nail when the user holds the trigger depressed first and then "bumps" the nail gun tip against the workpiece. With a full sequential actuation trigger (SAT) the user must press the tip against the workpiece prior to activating the trigger. The SAT is demonstrably safer in reducing traumatic injury risk, but increases the duration (and magnitude) of tip force exertion. Time integrated (cumulative) hand force was calculated for a single user from measurements of the tip contact force with the workpiece and transfer time between nails as inputs to a static model of the nail gun and workpiece in two nailing task orientations. The model shows the hand force dependence upon the orientation of the workpiece in addition to the trigger system. Based on standard time allowances from work measurement systems (i.e. Methods-Time Measurement - 1) it is proposed that efficient application of hand force with the SAT in maintaining tip contact can reduce force exertion attributable to the sequential actuation trigger to 2-8% (horizontal nailing) and 9-20% (vertical nailing) of the total hand/arm force. The present model is useful for considering differences in cumulative hand/arm force exposure between the SAT and CAT systems and may explain the appeal of the CAT trigger in reducing the user's perception of muscular effort.

中文翻译：

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使用气动射钉枪驱动系统对手/臂力进行生物力学评估

提出了一个生物力学模型，并结合尖端压力的测量，以估计与两个气动射钉枪触发系统相关的总用户手力。当用户首先按下扳机然后将射钉枪尖端“撞击”在工件上时，接触致动扳机 (CAT) 可以发射钉子。对于完整的顺序致动触发器 (SAT)，用户必须在激活触发器之前将尖端压在工件上。SAT 在降低外伤风险方面明显更安全，但会增加尖端力量施加的持续时间（和幅度）。根据尖端与工件的接触力和钉子之间的转移时间的测量，计算单个用户的时间积分（累积）手力，作为两个钉钉任务方向中钉枪和工件的静态模型的输入。除了触发系统之外，该模型还显示了手力依赖于工件的方向。基于工作测量系统（即方法-时间测量 - 1）的标准时间裕量，建议使用 SAT 有效应用手力以保持尖端接触可以将归因于顺序致动触发器的力施加减少到 2-8%（水平钉）和总手/臂力的 9-20%（垂直钉）。