站立動作是一複雜性動作，它包括了神經系統的控制及肌肉的反應等，我們可將之簡單的區分為神經性及機械性的動作。之前的論文對運動模型的探討多僅止於各肢幹的的運動力學，或以簡單的機械模型如倒擺來討論運動狀況。在我們的論文中，將以一多體模型來模擬人體平衡時的動作，且試圖討論踝關節、膝關節、髖關節勁度與阻尼值與肢幹運動力學間之相關性。我們將數學模型推廣到平衡運動時常用的三個關節的運動上，並依據Cavagna學者的假設，以彈簧及阻尼運動元件來描述連結各肢幹的肌肉、軟組織的彈性特性，採用三組彈簧、阻尼、質量塊等機械元件組成的多體模型來模擬進行平衡運動的個體，並利用Lagrange's Equation推導運動方程式。討論並比較所求出的k、c值。最後希望能夠獲得對k、c值對運動關係的深入瞭解。
實驗共有八位受測者。實驗一是請受測者分別站在力板上及一平衡半圓形板上，保持身體平衡。實驗二，請受測者分別以踝關節、膝關節、髖關節做主動的關節彎曲動作，在彎曲一關節的同時，盡量保持其他關節不彎曲。實驗三，在站立板上於重心位置給一瞬時外力。實驗四，在站平衡板上於重心位置給一瞬時外力，改變其初始狀況，討論k、c值的變化。
結果發現以程式求出之靜態時的k、c值較先前論文以直接量測法估算出之值來的高。動態時之k、c值較靜態時來的小。與先前學者提出傾斜角度會隨著勁度的增加而減少相符合。文中並提出以區段式求解動態時之k、c值，於解方程式時能得到較佳解。

Normal standing is a complex activity both mechanically and neurologically. Using Lagrange’s equation, we validated the three spring-damper-mass model for sagittal sway. Our approach was to derive the multi-segment model and employed springs and dampers to describe muscles and soft tissues characteristic, thus to simplify the complex system in order to gain an insight into the underlying principles of balance activity.
There were eight subjects participating in this study. With four separate trials, the subjects were ask to keep balance both on force plate and on the balance plate, which was free to move forwards and backwards. The four trial conditions were (1) stand still on force plate and balance plate, (2) stand on force plate with single joint movement, (3) stand on force plate and keep balance when exerting an impulse force to the subject, (4) stand on balance plate and keep balance when exerting an impulse force to the subject.
Results showed that the k、c value increased when the sway size was decreased, and also revealed that positive or negative of the k、c value may changed when the sway size was almost zero or when the sway was going to change its direction . As the stiffness frequency do different between subjects when doing the same trial, this implies stiffness may be used as the dynamic balance evaluation coefficient.

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