Pennsylvania State University, 39 Recreation Building, University Park, PA 16802, USA.
Exp Brain Res. 2011 Aug;213(1):125-39. doi: 10.1007/s00221-011-2784-y. Epub 2011 Jul 7.
When people transport handheld objects, they change the grip force with the object movement. Circular movement patterns were tested within three planes at two different rates (1.0, 1.5 Hz) and two diameters (20, 40 cm). Subjects performed the task reasonably well, matching frequencies and dynamic ranges of accelerations within expectations. A mathematical model was designed to predict the applied normal forces from kinematic data. The model is based on two hypotheses: (a) the grip force changes during movements along complex trajectories can be represented as the sum of effects of two basic commands associated with the parallel and orthogonal manipulation, respectively; (b) different central commands are sent to the thumb and virtual finger (Vf-four fingers combined). The model predicted the actual normal forces with a total variance accounted for of better than 98%. The effects of the two components of acceleration-along the normal axis and the resultant acceleration within the shear plane-on the digit normal forces are additive.
当人们搬运手持物体时，他们会随着物体的运动改变握持力。在三个平面内以两种不同的速率（1.0、1.5 Hz）和两种直径（20、40 cm）测试了圆形运动模式。受试者完成任务的情况相当好，在预期范围内匹配了加速度的频率和动态范围。设计了一个数学模型，根据运动学数据预测所施加的法向力。该模型基于两个假设：（a）在沿着复杂轨迹的运动过程中，握持力的变化可以表示为与平行和正交操作分别相关的两个基本命令的效果之和；（b）向拇指和虚拟手指（Vf-四指组合）发送不同的中央命令。该模型预测实际法向力的总方差占比超过 98%。沿法向轴的加速度和剪切平面内的合成加速度的两个分量对指力的影响是相加的。
