Burdet E, Osu R, Franklin D W, Yoshioka T, Milner T E, Kawato M
Department of Mechanical Engineering, National University of Singapore, 119260, Singapore.
J Biomech. 2000 Dec;33(12):1705-9. doi: 10.1016/s0021-9290(00)00142-1.
Current methods for measuring stiffness during human arm movements are either limited to one-joint motions, or lead to systematic errors. The technique presented here enables a simple, accurate and unbiased measurement of endpoint stiffness during multi-joint movements. Using a computer-controlled mechanical interface, the hand is displaced relative to a prediction of the undisturbed trajectory. Stiffness is then computed as the ratio of restoring force to displacement amplitude. Because of the accuracy of the prediction (< 1 cm error after 200 ms) and the quality of the implementation, the movement is not disrupted by the perturbation. This technique requires only 13 as many trials to identify stiffness as the method of Gomi and Kawato (1997, Biological Cybernetics 76, 163-171) and may, therefore, be used to investigate the evolution of stiffness during motor adaptation.
当前用于测量人体手臂运动过程中刚度的方法要么局限于单关节运动，要么会导致系统误差。本文提出的技术能够在多关节运动过程中对端点刚度进行简单、准确且无偏差的测量。通过使用计算机控制的机械接口，使手部相对于未受干扰轨迹的预测值产生位移。然后将刚度计算为恢复力与位移幅度的比值。由于预测的准确性（200毫秒后误差<1厘米）以及实施的质量，运动不会因扰动而中断。与Gomi和Kawato（1997年，《生物控制论》76卷，第163 - 171页）的方法相比，该技术确定刚度所需的试验次数仅为其1/3，因此可用于研究运动适应过程中刚度的演变。
