Hassan Elizabeth A, Jenkyn Thomas R, Dunning Cynthia E
Department of Mechanical and Materials Engineering, The University of Western Ontario, London, Ont., Canada.
J Biomech. 2007;40(4):930-5. doi: 10.1016/j.jbiomech.2006.03.019. Epub 2006 May 26.
The purpose of this study was to quantify the dynamic accuracy of kinematics measured by a digital optical motion analysis system in a gait analysis laboratory (capture volume approximately 20m(3)) compared to a standard range direct-current electromagnetic (EM) tracking device (capture volume approximately 1m(3)). This is a subset of a larger effort to establish an appropriate marker set for the optical system to quantify upperlimb kinematics simultaneously with gait, in comparison to previous studies of isolated upperlimb movements that have employed EM tracking devices. Rigid clusters of spherical reflective markers and EM sensors were attached to a mechanical articulator that mimicked three-dimensional joint rotations, similar to the elbow. As the articulator was moved through known ranges of motion (i.e. gold standard), kinematic data were collected simultaneously using both tracking systems. Both systems were tended to underestimate the range of motion; however, the application of post hoc smoothing and least-squares correction algorithms reduced these effects. When smoothing and correction algorithms were used, the magnitude of the mean difference between the gold standard and either the EM or optical system did not exceed 2 degrees for any of the compound motions performed. This level of agreement suggests that the measurements obtained from either system are clinically comparable, provided appropriate smoothing and correction algorithms are employed.
本研究的目的是，在步态分析实验室（采集体积约20立方米）中，将数字光学运动分析系统测量的运动学动态精度与标准范围的直流电磁（EM）跟踪设备（采集体积约1立方米）进行量化比较。这是一项更大规模工作的一部分，即与之前采用EM跟踪设备对孤立上肢运动的研究相比，为光学系统建立一套合适的标记集，以便在测量步态的同时量化上肢运动学。将球形反射标记和EM传感器的刚性簇附着到一个模拟三维关节旋转的机械关节器上，类似于肘部。当关节器在已知的运动范围内移动（即黄金标准）时，使用两个跟踪系统同时收集运动学数据。两个系统都倾向于低估运动范围；然而，事后平滑和最小二乘校正算法的应用减少了这些影响。当使用平滑和校正算法时，对于所执行的任何复合运动，黄金标准与EM或光学系统之间的平均差异幅度均不超过2度。这种一致程度表明，只要采用适当的平滑和校正算法，从任一系统获得的测量结果在临床上具有可比性。
