Department of Engineering Science and Mechanics (MC 0219), Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
J Biomech. 2010 Apr 19;43(6):1220-3. doi: 10.1016/j.jbiomech.2009.11.036. Epub 2010 Jan 4.
Moments measured by a dynamometer in biomechanics testing often include the gravitational moment and the passive elastic moment in addition to the moment caused by muscle contraction. Gravitational moments result from the weight of body segments and dynamometer attachment, whereas passive elastic moments are caused by the passive elastic deformation of tissues crossing the joint being assessed. Gravitational moments are a major potential source of error in dynamometer measurements and must be corrected for, a procedure often called gravity correction. While several approaches to gravity correction have been presented in the literature, they generally assume that the gravitational moment can be adequately modeled as a simple sine or cosine function. With this approach, a single passive data point may be used to specify the model, assuming that passive elastic moments are negligible at that point. A new method is presented here for the gravity correction of dynamometer data. Gravitational moment is represented using a generalized sinusoid, which is fit to passive data obtained over the entire joint range of motion. The model also explicitly accounts for the presence of passive elastic moments. The model was tested for cases of hip flexion-extension, knee flexion-extension, and ankle plantar flexion-dorsiflexion, and provided good fits in all cases.
在生物力学测试中，测功计测量的力矩除了肌肉收缩引起的力矩外，通常还包括重力矩和被动弹性矩。重力矩是由身体各部分和测力计附件的重量引起的，而被动弹性矩是由经过评估的关节处的组织被动弹性变形引起的。重力矩是测力计测量中的一个主要潜在误差源，必须进行校正，这一过程通常称为重力校正。虽然文献中已经提出了几种重力校正方法，但它们通常假设重力矩可以很好地用简单的正弦或余弦函数来建模。使用这种方法，可以使用单个被动数据点来指定模型，假设在该点处被动弹性矩可以忽略不计。本文提出了一种新的测力计数据重力校正方法。重力矩采用广义正弦函数表示，该函数适用于整个关节运动范围内获得的被动数据。该模型还明确考虑了被动弹性矩的存在。该模型在髋关节屈伸、膝关节屈伸和踝关节跖屈-背屈的情况下进行了测试，在所有情况下都得到了很好的拟合。
