Forces and moments generated by the human arm: variability and control.
Forces and moments generated by the human arm: variability and control.
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DOI：
10.1007/s00221-012-3235-0
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发表时间：
2012-11
影响因子：
2
通讯作者：
Zatsiorsky, V. M.
中科院分区：
文献类型：
--
作者：
Xu, Y.;Terekhov, A. V.;Latash, M. L.;Zatsiorsky, V. M.
这是一项探索性研究，在等长条件下，由人臂产生精确的终点力矢量。我们提出了三个常识性的假设，并在实验中证明了它们。受试者（n=10）在水平面内的八个方向上对手柄施加静态力25秒。力为4个量级水平（单个MVC的10%、20%、30%和40%）。说明书中未规定手柄上的扭矩（抓握力矩）。记录两个力分量和抓握力矩，并计算肩、肘和腕关节扭矩。观察到以下主要事实：（a）虽然抓握力矩不是由指令规定的，但它总是产生的。力矩的大小和方向取决于指令力的大小和方向。(b)施加力矢量的试验内角度变异性（角度精度）不取决于目标力大小（观察到较小的负相关性）。(c)在目标力方向上，施加力大小的变异性和方向变异性表现出相反的趋势：在力大小变异性最大的方向上，方向变异性最小，反之亦然。(d)试验中关节扭矩的时间曲线始终呈正相关，即使是在一个关节产生屈曲扭矩和另一个关节产生伸展扭矩的力方向。(e)抓握力矩和手腕扭矩之间的相关性在整个任务中是负的，在单个试验中是正的。(f)在静态串联运动链中，各关节力矩的分布规律不能用优化代价函数关于力矩的可加性来解释。已经提出了未来几项实验的计划。
This is an exploratory study of the accurate endpoint force vector production by the human arm in isometric conditions. We formulated three common-sense hypotheses and falsified them in the experiment. The subjects (n=10) exerted static forces on the handle in eight directions in a horizontal plane for 25 seconds. The forces were of 4 magnitude levels (10 %, 20%, 30% and 40% of individual MVC). The torsion moment on the handle (grasp moment) was not specified in the instruction. The two force components and the grasp moment were recorded, and the shoulder, elbow, and wrist joint torques were computed. The following main facts were observed: (a) While the grasp moment was not prescribed by the instruction, it was always produced. The moment magnitude and direction depended on the instructed force magnitude and direction. (b) The within-trial angular variability of the exerted force vector (angular precision) did not depend on the target force magnitude (a small negative correlation was observed). (c) Across the target force directions, the variability of the exerted force magnitude and directional variability exhibited opposite trends: In the directions where the variability of force magnitude was maximal, the directional variability was minimal and vice versa. (d) The time profiles of joint torques in the trials were always positively correlated, even for the force directions where flexion torque was produced at one joint and extension torque was produced at the other joint. (e) The correlations between the grasp moment and the wrist torque were negative across the tasks and positive within the individual trials. (f) In static serial kinematic chains, the pattern of the joint torques distribution could not be explained by an optimization cost function additive with respect to the torques. Plans for several future experiments have been suggested.
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影响因子：
2
作者：
Park, Jaebum;Singh, Tarkeshwar;Zatsiorsky, Vladimir M.;Latash, Mark L.
通讯作者：
Latash, Mark L.
影响因子：
64.8
作者：
Harris, CM;Wolpert, DM
通讯作者：
Wolpert, DM
影响因子：
2
作者：
Gao, F;Latash, ML;Zatsiorsky, VM
通讯作者：
Zatsiorsky, VM
影响因子：
1.4
作者：
Friedman, Jason;Latash, Mark L.;Zatsiorsky, Vladimir M.
通讯作者：
Zatsiorsky, Vladimir M.
影响因子：
2
作者：
Kapur, Shweta;Friedman, Jason;Zatsiorsky, Vladimir M.;Latash, Mark L.
通讯作者：
Latash, Mark L.