Lin M L, Radwin R G, Snook S H
Department of Industrial Engineering, University of Wisconsin-Madison 53706, USA.
Ergonomics. 1997 May;40(5):543-58. doi: 10.1080/001401397188026.
The relative effects of repetition, force and posture were studied in order to investigate how continuous biomechanical measurements can be combined into a single metric corresponding to subjective discomfort. A full factorial experiment was conducted involving repetitive wrist flexion from a neutral posture to a given angle against a controlled force. Seven subjects performed the task using two paces (20 and 4 motions/min), two force levels (15 and 45 N) and two angles (15 and 45 degrees) for 1 h each. Discomfort was reported on a 10 cm visual analogue scale anchored between 'no discomfort' and 'very high discomfort'. Repeated measures analysis of variance showed that all main effects were statistically significant (p < 0.05) and no significant interactions were observed. A linear regression model was fitted to the data and used for generating frequency weighted digital filters that shape continuous recordings of repetitive motions and exertions into an output proportional to relative discomfort. The resulting high-pass digital filter had a 22 dB/decade attenuation slope. A simulated industrial task used for validating the model involved repetitively transferring pegs across a horizontal bar and inserting them into holes against a controlled resistance. Angular wrist data were recorded using an electrogoniometer and filtered. Six subjects performed the task of the three conditions consisting of (1) 15 wrist flexion, 15 N resistance and 6 motions min, (2) 15 wrist flexion. 45 N resistance and 12 motions/min, and (3) 45 degrees wrist flexion, 45 N resistance and 15 motions/min. Subjective discomfort was reported after performing the task for 1 h. Pearson correlations between subjective discomfort ratings and the integrated filtered biomechanical data for individual subjects ranged from 0.90 to 1.00. The pooled correlation across subjects was 0.67. This approach may be useful for physical stress exposure assessment and for design of tasks involving repetitive motions and exertions.
为了研究如何将连续的生物力学测量结果整合为一个与主观不适相对应的单一指标，对重复、力量和姿势的相对影响进行了研究。进行了一项全因子实验，实验内容是让受试者从自然姿势开始，以一定的力量向给定角度进行重复性的手腕弯曲。七名受试者分别以两种速度（每分钟20次和4次动作）、两种力量水平（15牛顿和45牛顿）和两个角度（15度和45度）完成任务，每次持续1小时。受试者通过10厘米长的视觉模拟量表报告不适程度，量表两端分别标记为“无不适”和“非常不适”。重复测量方差分析表明，所有主效应均具有统计学意义（p < 0.05），且未观察到显著的交互作用。对数据拟合了一个线性回归模型，并用于生成频率加权数字滤波器，该滤波器将重复运动和用力的连续记录整形为与相对不适成比例的输出。所得的高通数字滤波器具有22分贝/十倍频程的衰减斜率。用于验证该模型的模拟工业任务包括在水平杆上反复转移栓子，并在可控阻力下将其插入孔中。使用电子测角仪记录手腕角度数据并进行滤波。六名受试者在三种条件下完成任务，这三种条件分别为：（1）15度手腕弯曲、15牛顿阻力和每分钟6次动作；（2）15度手腕弯曲、45牛顿阻力和每分钟12次动作；（3）45度手腕弯曲、45牛顿阻力和每分钟15次动作。在完成任务1小时后报告主观不适程度。个体受试者的主观不适评分与综合滤波后的生物力学数据之间的皮尔逊相关系数在0.90至1.00之间。所有受试者的合并相关系数为0.67。这种方法可能有助于进行身体应激暴露评估以及涉及重复运动和用力的任务设计。
