Reid M M, Campbell Amity C, Elliott B C
Tennis Australia, Australia.
J Appl Biomech. 2012 Feb;28(1):93-8. doi: 10.1123/jab.28.1.93. Epub 2011 Oct 4.
Tennis stroke mechanics have attracted considerable biomechanical analysis, yet current filtering practice may lead to erroneous reporting of data near the impact of racket and ball. This research had three aims: (1) to identify the best method of estimating the displacement and velocity of the racket at impact during the tennis serve, (2) to demonstrate the effect of different methods on upper limb kinematics and kinetics and (3) to report the effect of increased noise on the most appropriate treatment method. The tennis serves of one tennis player, fit with upper limb and racket retro-reflective markers, were captured with a Vicon motion analysis system recording at 500 Hz. The raw racket tip marker displacement and velocity were used as criterion data to compare three different endpoint treatments and two different filters. The 2nd-order polynomial proved to be the least erroneous extrapolation technique and the quintic spline filter was the most appropriate filter. The previously performed "smoothing through impact" method, using a quintic spline filter, underestimated the racket velocity (9.1%) at the time of impact. The polynomial extrapolation method remained effective when noise was added to the marker trajectories.
网球击球动作机制已吸引了大量的生物力学分析，但目前的滤波方法可能会导致在球拍与球碰撞附近的数据报告出现错误。本研究有三个目的：（1）确定在网球发球过程中估计球拍在碰撞时的位移和速度的最佳方法，（2）展示不同方法对上肢运动学和动力学的影响，以及（3）报告增加噪声对最合适处理方法的影响。一名网球运动员的网球发球动作，通过在其上肢和球拍上安装反光标记进行捕捉，使用Vicon运动分析系统以500Hz的频率进行记录。原始的球拍尖端标记位移和速度用作标准数据，以比较三种不同的端点处理方法和两种不同的滤波器。结果证明二阶多项式是误差最小的外推技术，而五次样条滤波器是最合适的滤波器。先前使用五次样条滤波器执行的“通过碰撞进行平滑处理”方法，低估了碰撞时的球拍速度（9.1%）。当在标记轨迹中添加噪声时，多项式外推方法仍然有效。
