Lujan Trevor J, Lake Spencer P, Plaizier Timothy A, Ellis Benjamin J, Weiss Jeffrey A
Department of Bioengineering and Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT 84112, USA.
J Biomech Eng. 2005 Feb;127(1):193-7. doi: 10.1115/1.1835365.
The objective of this study was to assess the precision and accuracy of a nonproprietary, optical three-dimensional (3D) motion analysis system for the simultaneous measurement of soft tissue strains and joint kinematics. The system consisted of two high-resolution digital cameras and software for calculating the 3D coordinates of contrast markers. System precision was assessed by examining the variation in the coordinates of static markers over time. Three-dimensional strain measurement accuracy was assessed by moving contrast markers fixed distances in the field of view and calculating the error in predicted strain. Three-dimensional accuracy for kinematic measurements was assessed by simulating the measurements that are required for recording knee kinematics. The field of view (190 mm) was chosen to allow simultaneous recording of markers for soft tissue strain measurement and knee joint kinematics. Average system precision was between +/-0.004 mm and +/-0.035 mm, depending on marker size and camera angle. Absolute error in strain measurement varied from a minimum of +/-0.025% to a maximum of +/-0.142%, depending on the angle between cameras and the direction of strain with respect to the camera axes. Kinematic accuracy for translations was between +/-0.008 mm and +/-0.034 mm, while rotational accuracy was +/-0.082 deg to +/-0.160 deg. These results demonstrate that simultaneous optical measurement of 3D soft tissue strain and 3D joint kinematics can be performed while achieving excellent accuracy for both sets of measurements.
本研究的目的是评估一种非专利的光学三维（3D）运动分析系统在同时测量软组织应变和关节运动学时的精度和准确性。该系统由两台高分辨率数码相机和用于计算对比标记物三维坐标的软件组成。通过检查静态标记物坐标随时间的变化来评估系统精度。通过在视野中移动固定距离的对比标记物并计算预测应变的误差来评估三维应变测量精度。通过模拟记录膝关节运动学所需的测量来评估运动学测量的三维准确性。选择视野（190毫米）以允许同时记录用于软组织应变测量和膝关节运动学的标记物。平均系统精度在+/-0.004毫米至+/-0.035毫米之间，具体取决于标记物大小和相机角度。应变测量的绝对误差根据相机之间的角度和应变相对于相机轴的方向，从最小的+/-0.025%到最大的+/-0.142%不等。平移的运动学精度在+/-0.008毫米至+/-0.034毫米之间，而旋转精度为+/-0.082度至+/-0.160度。这些结果表明，可以同时进行三维软组织应变和三维关节运动学的光学测量，同时两组测量都能达到优异的精度。
