由於機器在工作環境之適應性需求增加，因此相較於只具一固定勁度之機器，具可變勁度者是更好的選擇。因為在文獻中的變勁度機構大多為旋轉式，因此本論文以預載法設計一新型直線式變勁度機構，其設計概念為並聯兩側向曲樑及一軸向彈簧，並透過施於曲樑之預載調整，使其輸出之力量-位移曲線的勁度不同。而所提出之直線式變勁度機構的優點在於機構可在一緊密之空間中達成大勁度可調度，除了達成勁度可調外，此設計與其他設計不同處在於可藉由搭配適當勁度之軸向彈簧，使機構勁度可調整至零勁度。而為了不失一般性，本論文探討曲樑兩端在旋轉接頭及固定之邊界條件下的影響。另外，為了在具有足夠之線性度的情況下達到最大的勁度可調度，本論文討論給定參數對機構特性的影響。而本文也介紹如何縮放機構尺寸及改變機構之平衡位置，以增加此設計之用途。最後，藉由實驗驗證所提出之設計概念。

Due to the increasing demand on the adaptability in working environments, a machine with a variable stiffness is preferable to that with a constant stiffness. Because variable-stiffness mechanisms found in the literature are mostly rotary type. This thesis presents the design of a class of novel linear variable-stiffness mechanisms (LVSMs). The idea is to parallel connect two lateral curved beams with an axial spring. Through preload adjustment of the curved beams, the output force-to-displacement curves can exhibit different stiffness. The merit of the proposed LVSMs is that large stiffness variation can be achieved in a compact space. In addition to achieving variable stiffness, the presented work differs from previous ones is that the stiffness can be tuned to zero by assigning a proper stiffness to the axial spring. Without loss of generality, this thesis investigates curved beams with pinned and fixed boundary conditions. To achieve the largest stiffness variation with sufficient linearity, the effects of various parameters are discussed. Techniques to scale an LVSM and change the equilibrium position are introduced to enhance the usefulness of the proposed design. Finally, the presented design concepts are experimentally verified through prototypes.

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