模拟跳伞着陆时的运动学特征

6名伞兵在跳伞平台上模拟跳伞着陆,采用高速摄影法记录,观察着陆姿势、着陆时的位移、速度和加速度等运动学特征,结果:①无负荷时,人体的重心较高,脊柱轴线与铅垂线的夹角较小;有负荷时相反。②有负荷时,耳屏、髂前上棘、大粗隆、桡骨、桡骨茎突和指尖等点在水平方向上的位移范围较大,在铅垂线方向上较分散;无负荷时相反,③有负荷时,各观测标记点的速度和加速度较大,且运动时间较长;无负荷时相反。④有负荷时,各节段与铅垂线的夹角比无负荷时大,大腿与小腿间、小腿与跖底平面间的夹角比无负荷时小,即有负荷时该相邻节段的弯曲度较大,无负荷时相反。上述运功学特征提示一条探索减小着陆冲击力的途径。

Kinematic Characteristics of Human Body during Landing in Simulated Parachuted Jumping

Such kinematic characteristics as the postures, the displacement, the velocity and the acceleration during landing were studied by using high-speed photography in six young healthy male parachuters jumping from a platform. The results showed that; (1) from the figure of the landing posture when the subjects were unloaded, the center of the human body gravity was higher and the angle between the spinal axis and the plumb line smaller; when loaded, the above-mentioned results were the opposite. (2) When the subjects were loaded, the horizontal displacements of the tragion, the iliospinal anterius, the trochanterian, the radiale, the stylion radiale and the dactylion , were larger than those when unloaded. The distribution of the above-mentioned points was dispersive on the plumb line. The results were the opposite when unloaded. (3) When loaded, the velocity and acceleration observe.d from each mark on the human body were rapid, and their motional time was long. When unloaded, the results were the opposite. (4) The angles between the various body segments and the plumb line were larger when loaded than when unloaded. When loaded, the angles between the shank and the thigh, and between the shank and the plantar were smaller than those when unloaded, that is, the flexures of the adjacent segments were larger when loaded than when unloaded. The above-mentioned kinematic characteristics suggest a way of reducing the landing impact force, which is of significance to the study of the correct landeng posture.