调整期内大腿相对躯干转动的运动学分析

Kinematic Analysis of the Rotations of Two Thighs Relative to Trunk during the Adjustment Period in Ski jumping

根据刚体的有限转动可分解为依一定顺序绕连体基不同基矢量的 3次有限转动的原理 ,推导了跳雪运动员在调整期内两条大腿相对躯干的方向转换矩阵和角速度的计算公式。按照公式编制了 MATL AB程序 ,对运动员刘树明在其调整期内大腿相对躯干的方位和角速度随时间的变化规律进行了计算 ,证明了公式的有效性 ,并且发现左、右大腿相对躯干的转动角速度在自身随体坐标系中的投影呈现强烈的“波动性”

In accordance with the principle that a finite rotation of rigid body can be divided into three rotations around different basic vectors of body fixed base in particular order, a formula is deduced to calculate the directional transformation matrices and rotational velocities of two thighs of a ski jumper relative to the trunk during the adjustment period. The MATLAB program was developed and the variations of the orientations and rotational velocities of the two thighs relation to the trunk during the adjustment period were calculated for a jumper named Liu Shuming. The validity of the formula was proved and it was found that the projection rotational velocities of the two thighs relative to the trunk in his own body fixed coordinates showed a strong fluctuation.