Revilla Josefa Angelie, Priadythama Ilham, Loh Ping Yeap, Muraki Satoshi
Department of Industrial Engineering, University of the Philippines Los Baños, Laguna, Philippines.
Graduate School of Design, Kyushu University, Fukuoka, Japan.
J Occup Environ Hyg. 2022 Jun;19(6):353-369. doi: 10.1080/15459624.2022.2063877. Epub 2022 May 4.
The magnitude of hand- (HTV) and wrist- (WTV) transmitted vibration can negatively impact upper limb responses even during short-term exposure. This study aimed to establish the effects of various handle-grip designs on the harmful impacts of vibration, sustained grip exertion, and unnatural posture. The primary focus was to investigate how using a handle grip and how three shapes with two surface profiles affect HTV, WTV, and forearm muscle activities during exposure. The secondary goal was to evaluate the immediate effects on fundamental hand functions, perceived discomfort/comfort, and perceived vibration level after exposure. The final objective was to assess which of the handle designs had the least harmful effects. Fourteen young male adults were recruited and asked to consistently grip a vibrating handle structure for 2 min while the primary parameters were recorded. Pre- and post-task measurements of secondary parameters were recorded on the six design conditions and one control condition (no handle grip). The study found that implementing a regular circular-smooth handle resulted in lower transmitted vibrations, leading to lower upper-limb discomfort, higher grip comfort, and lower perceived vibration. Additionally, shape significantly affected HTV, resulting in grip strength reduction, while surface profile did not influence transmitted vibrations but significantly impacted ring and small finger sensitivity, finger and hand discomfort, and grip comfort. Finally, forearm muscle activities were unaffected, and no significant interaction effects were observed. Circular handles also had the least negative impacts, and elliptic handles had the most negative impacts on the upper extremity because of the level of hand-handle contact stress and hand-grip effort. Meanwhile, the uneven distribution of vibration on the fingers and palm imposed by the rounded spikes on the patterned surface led to decreased finger sensitivity, higher discomfort, and lower grip comfort. Therefore, when machine operation involves moderate grip exertion, pronated forearm posture, and short-term handle vibration exposure, implementing a hard-solid handle with less hand-handle contact area, less grip effort, and even texture is recommended.
即使在短期暴露期间，手部（HTV）和腕部（WTV）传递的振动强度也会对上肢反应产生负面影响。本研究旨在确定各种手柄握持设计对振动、持续握持用力和不自然姿势的有害影响。主要重点是研究使用手柄握持以及三种形状与两种表面轮廓如何在暴露期间影响HTV、WTV和前臂肌肉活动。次要目标是评估暴露后对基本手部功能、感知的不适/舒适以及感知的振动水平的即时影响。最终目标是评估哪种手柄设计的有害影响最小。招募了14名年轻男性成年人，要求他们持续握持振动手柄结构2分钟，同时记录主要参数。在六种设计条件和一种对照条件（无手柄握持）下记录任务前后的次要参数测量值。研究发现，采用规则的圆形光滑手柄可降低传递的振动，从而降低上肢不适、提高握持舒适度并降低感知振动。此外，形状对HTV有显著影响，导致握力降低，而表面轮廓不影响传递的振动，但对无名指和小指的敏感度、手指和手部不适以及握持舒适度有显著影响。最后，前臂肌肉活动未受影响，未观察到显著的交互作用。由于手与手柄的接触应力水平和握力，圆形手柄对上肢的负面影响也最小，椭圆形手柄的负面影响最大。同时，有图案表面上的圆形尖刺导致手指和手掌上振动分布不均，从而导致手指敏感度降低、不适感增加和握持舒适度降低。因此，当机器操作涉及适度的握持用力、旋前的前臂姿势和短期手柄振动暴露时，建议使用具有较小手与手柄接触面积、较小握力和均匀质地的硬实手柄。
