Department of Physical Medicine and Rehabilitation, Rehabilitation Institute of Chicago, Northwestern University, 345 E Superior St., Room 1479, Chicago, IL 60611, USA.
Exp Brain Res. 2011 Dec;215(3-4):247-55. doi: 10.1007/s00221-011-2889-3. Epub 2011 Oct 14.
The measurement of body and limb posture is important to many clinical and research studies. Current approaches either directly measure posture (e.g., using optical or magnetic methods) or more indirectly measure it by integrating changes over time (e.g., using gyroscopes and/or accelerometers). Here, we introduce a way of estimating posture from movements without requiring integration over time and the resulting complications. We show how the almost imperceptible tremor of the hand is affected by posture in an intuitive way and therefore can be used to estimate the posture of the arm. We recorded postures and tremor of the arms of volunteers. By using only the minor axis in the covariance of hand tremor, we could estimate the angle of the forearm with a standard deviation of about 4° when the subject's elbow is resting on a table and about 10° when it is off the table. This technique can also be applied as a post hoc analysis on other hand-position data sets to extract posture. This new method allows the estimation of body posture from tremor, is complementary to other techniques, and so can become a useful tool for future research and clinical applications.
身体和肢体姿势的测量对于许多临床和研究研究都很重要。目前的方法要么直接测量姿势（例如，使用光学或磁性方法），要么通过随时间的积分更间接测量姿势（例如，使用陀螺仪和/或加速度计）。在这里，我们介绍了一种无需随时间积分及其带来的复杂性即可从运动中估计姿势的方法。我们直观地展示了手的几乎察觉不到的震颤如何受到姿势的影响，因此可以用于估计手臂的姿势。我们记录了志愿者手臂的姿势和震颤。通过仅在手震颤协方差的短轴上使用，当主体的肘部放在桌子上时，我们可以以约 4°的标准偏差估计前臂的角度，当它离开桌子时，约为 10°。该技术也可以应用于其他手位数据集的事后分析以提取姿势。这种新方法允许从震颤中估计身体姿势，与其他技术互补，因此可以成为未来研究和临床应用的有用工具。
