Kingma I, Toussaint H M, Commissaris D A, Hoozemans M J, Ober M J
Faculty of Human Movement Science, Vrije Universiteit, Amsterdam, The Netherlands.
J Biomech. 1995 Sep;28(9):1137-42. doi: 10.1016/0021-9290(94)00164-y.
The position or trajectory of the body center of mass (COM) is often a parameter of interest when studying posture or movement. For instance, in balance control studies the body COM can be related to the ground reaction force or to the base of support. Since small displacements of the body COM are important in balance control studies, it is essential to obtain valid estimates of the body COM. The main source of error in the determination of the body COM is the estimation of the masses and centers of mass of the body segments. Especially the determination of the trunk COM is prone to error. In the current study five subjects maintained three postures, differing in trunk angle, during a few seconds. The relation between the center of pressure of the ground reaction force and the vertical projection of the body COM during the postures was used to optimize the trunk COM position. Additionally the subjects performed two lifting movements. The validity of the body COM trajectory estimation during the lifting movements, both with and without optimized trunk COM, was checked by relating the external moment of the ground reaction force with respect to the body COM to the rate of change of the angular momentum of the whole body. It was shown that the correspondence between the external moment and the rate of change of the angular momentum improved after optimization of the trunk COM. This suggests that the body COM trajectory estimation can be improved by the proposed optimization procedure.
在研究姿势或运动时，身体重心（COM）的位置或轨迹通常是一个重要参数。例如，在平衡控制研究中，身体重心可与地面反作用力或支撑面相关联。由于身体重心的微小位移在平衡控制研究中很重要，因此获得身体重心的有效估计至关重要。确定身体重心时的主要误差来源是身体各节段质量和质心的估计。特别是躯干重心的确定容易出现误差。在本研究中，五名受试者在几秒钟内保持了三种不同躯干角度的姿势。利用姿势期间地面反作用力的压力中心与身体重心垂直投影之间的关系来优化躯干重心位置。此外，受试者还进行了两次举重动作。通过将地面反作用力相对于身体重心的外力矩与全身角动量的变化率相关联，检验了在有和没有优化躯干重心的情况下，举重动作期间身体重心轨迹估计的有效性。结果表明，优化躯干重心后，外力矩与角动量变化率之间的对应关系得到改善。这表明，所提出的优化程序可以改善身体重心轨迹估计。
