Martin B J, Armstrong T J, Foulke J A, Natarajan S, Klinenberg E, Serina E, Rempel D
Center for Ergonomics, University of Michigan, Ann Arbor 48109-2117, USA.
Hum Factors. 1996 Dec;38(4):654-64. doi: 10.1518/001872096778827288.
This study examines the relationship between forearm EMGs and keyboard reaction forces in 10 people during keyboard tasks performed at a comfortable speed. A linear fit of EMG force data for each person and finger was calculated during static fingertip loading. An average r2 of .71 was observed for forces below 50% of the maximal voluntary contraction (MVC). These regressions were used to characterize EMG data in force units during the typing task. Averaged peak reaction forces measured during typing ranged from 3.33 N (thumb) to 1.84 N (little finger), with an overall average of 2.54 N, which represents about 10% MVC and 5.4 times the key switch make force (0.47 N). Individual peak or mean finger forces obtained from EMG were greater (1.2 to 3.2 times) than force measurements; hence the range of r2 for EMG force was .10 to .46. A closer correspondence between EMG and peak force was obtained using EMG averaged across all fingers. For 5 of the participants the force computed from EMG was within +/-20% of the reaction force. For the other 5 participants forces were overestimated. For 9 participants the difference between EMG estimated force and the reaction force was less than 13% MVC. It is suggested that the difference between EMG and finger force partly results from the amount of muscle load not captured by the measured applied force.
本研究考察了10名受试者在以舒适速度进行键盘操作任务时，前臂肌电图（EMG）与键盘反作用力之间的关系。在静态指尖加载过程中，计算了每个人每个手指的肌电图力数据的线性拟合。对于低于最大自主收缩（MVC）50%的力，观察到平均r2为0.71。这些回归用于在打字任务期间以力单位表征肌电图数据。打字过程中测得的平均峰值反作用力范围为3.33N（拇指）至1.84N（小指），总体平均值为2.54N，约占MVC的10%，是按键开关闭合力（0.47N）的5.4倍。从肌电图获得的个体峰值或平均手指力比力测量值更大（1.2至3.2倍）；因此，肌电图力的r2范围为0.10至0.46。使用所有手指的平均肌电图可获得肌电图与峰值力之间更紧密的对应关系。对于5名参与者，从肌电图计算出的力在反作用力的+/-20%范围内。对于其他5名参与者，力被高估。对于9名参与者，肌电图估计力与反作用力之间的差异小于13%MVC。研究表明，肌电图与手指力之间的差异部分是由于测量的作用力未捕获的肌肉负荷量所致。
