An Analysis of the Stiffness and Buffering Characteristics of a Bionic Leg

This paper presents a bionic leg that can buffer the impact from the ground based on the biologic researches. The leg consists of two rigid links and a linear extension spring. Firstly, the maximum expected compression of the bionic leg is calculated based on the bionic model and the geometric design of the leg is carried on according to the biologic data. Then, how to select the appropriate stiffness of the linear extension spring is explained while the nonlinear stiffness of the bionic leg is deduced. Moreover, through data fitting the nonlinear stiffness is expressed in a piecewise form that consists of a linear stiffness and a cubic stiffness. Finally, the numerical computation shows that the bionic leg can obtain low buffering index with parallel optimal damping ratio.