Wilson D J, Smith B K, Gibson J K, Choe B K, Gaba B C, Voelz J T
Department of Physical Medicine and Rehabilitation, Howard A Rusk Rehabilitation Center, University of Missouri-Columbia, 65212, USA.
Phys Ther. 1999 Jun;79(6):558-66.
Computerized 3-dimensional (3-D) motion measurement systems are used by those interested in human motion. The purposes of this study were (1) to determine the limits of accuracy in determining intersegmental angles during pendular motion at varying speeds and (2) to determine changes in accuracy introduced by autodigitization and digitization by experienced manual raters.
Angular speed of a T-shaped pendulum was systematically increased by releasing the pendulum from 4 angles (0 degrees [no movement], 45 degrees, 90 degrees, and 120 degrees). Twelve reference angles calculated from markers placed on the pendulum were estimated over 20 frames for 10 trials at each release position.
Mean errors across trials and frames for intersegmental angles reconstructed by a 3-D motion measurement system were within +/- 1 degree across all release positions. An analysis of variance and a post hoc Tukey test revealed that the mean error for the autodigitized trials was larger than that for the manually digitized trials. For the autodigitized trials, the static trials (release position=0 degrees) produced less mean error than the trials with movement produced. The ICCs showed a high degree of consistency among all raters, ranging from .707 to .999.
Our findings support the conclusion that under carefully controlled conditions, a 3-D motion measurement system can produce clinically acceptable measurements of accuracy across a range of angular speeds. Furthermore, acceptable accuracy is possible regardless of the digitization method.
对人体运动感兴趣的人士会使用计算机三维（3-D）运动测量系统。本研究的目的是：（1）确定在不同速度下的钟摆运动过程中，测定节段间角度时的精度极限；（2）确定自动数字化以及由经验丰富的人工评分者进行数字化所带来的精度变化。
通过从4个角度（0度[无运动]、45度、90度和120度）释放钟摆，系统地提高T形钟摆的角速度。在每个释放位置进行10次试验，在20帧内估计从放置在钟摆上的标记计算出的12个参考角度。
在所有释放位置，三维运动测量系统重建的节段间角度在各试验和各帧中的平均误差均在±1度以内。方差分析和事后Tukey检验显示，自动数字化试验的平均误差大于人工数字化试验的平均误差。对于自动数字化试验，静态试验（释放位置 = 0度）产生的平均误差小于有运动的试验。组内相关系数显示所有评分者之间具有高度一致性，范围从0.707到0.999。
我们的研究结果支持以下结论：在精心控制的条件下，三维运动测量系统能够在一系列角速度范围内产生临床上可接受的精度测量结果。此外，无论采用何种数字化方法，都有可能获得可接受的精度。
