THE INTERACTIONS BETWEEN TWO-SEGMENT STRIKING MOTION GENERATED BY PROXIMAL SEGMENT OF UPPER ARM

Abstract

The purpose of this study was to examine the kinetical interactions between two segments of the upper arm using the forward dynamics derived from Lagrange’s equation of motion, and then clarify the proximal-distal sequence. For the decades, open-linked, multi-segment systems were the important issues to biomechanists. But the more segments have been examined, the more complex the topic has become. Therefore, it is important to examine the effects of joint moment on upper extremities striking motion by simulation of two segments. To facilitate dynamic computation and to simplify the modeling, the upper arm of present study was modeled as a two linked-segment model with upper arm and forearm, in which the forearm and hand were treated as one segment. The summation of results is as follows: When the proximal segment was only given a constant moment (free the distal segment), the whole system displayed a proximal-distal sequence. Furthermore, the distal segment lead to the proximal segment, reaching maximum velocity. The motion presented a periodic fluctuation, and would maintain a straight position indefinitely if the duration of motion were sustained long enough.