Shin Duk, Kim Jaehyo, Koike Yasuharu
Precision and Intelligence Laboratory, Tokyo Institute of Technology, Yokohama, Japan.
J Neurophysiol. 2009 Jan;101(1):387-401. doi: 10.1152/jn.00584.2007. Epub 2008 Nov 12.
The perturbation method has been used to measure stiffness of the human arm with a manipulator. Results are averages of stiffness during short perturbation intervals (<0.4 s) and also vary with muscle activation. We therefore propose a novel method for estimating static arm stiffness from muscle activation without the use of perturbation. We developed a mathematical muscle model based on anatomical and physiological data to estimate joint torque solely from EMG. This model expresses muscle tension using a quadratic function of the muscle activation and parameters representing muscle properties. The parameters are acquired from the relation between EMG and measured torque. Using this model, we were able to reconstruct joint torque from EMG signals with or without co-contraction. Joint stiffness is directly obtained by differentiation of this model analytically. We confirmed that the proposed method can be used to estimate joint torque, joint stiffness, and stiffness ellipses simultaneously for various postures with the same parameters and produces results consistent with the conventional perturbation method.
已经使用微扰法通过操纵器测量人体手臂的刚度。结果是短微扰间隔（<0.4秒）期间刚度的平均值，并且也随肌肉激活而变化。因此，我们提出了一种无需微扰即可根据肌肉激活估计静态手臂刚度的新方法。我们基于解剖学和生理学数据开发了一个数学肌肉模型，仅从肌电图（EMG）估计关节扭矩。该模型使用肌肉激活的二次函数和代表肌肉特性的参数来表达肌肉张力。这些参数从肌电图与测量扭矩之间的关系中获取。使用该模型，我们能够从有无协同收缩的肌电信号中重建关节扭矩。通过对该模型进行解析微分直接获得关节刚度。我们证实，所提出的方法可用于使用相同参数同时估计各种姿势下的关节扭矩、关节刚度和刚度椭圆，并且产生与传统微扰法一致的结果。
