Abstract:

This paper presented a passive buffer leg mechanism which was used to isolate the ground impact on walking robots. The leg mechanism consisted of links, a linear tension spring and a linear damper. The equivalent stiffness of the leg mechanism was derived from geometric relation, and the effect of a few leg mechanism parameters on the stiffness was presented. The equivalent stiffness was expressed in piecewise as a cubic stiffness and a linear stiffness through data fitting. Then the displacement and acceleration responses during buffering were figured out through numerical computation. The three leg mechanisms with piecewise nonlinear stiffness,cubic nonlinear stiffness and linear stiffness were compared respectively in terms of their buffer coefficients. The result shows that when each leg mechanism connects to an optimal damping ratio in parallel, the leg mechanism with piecewise nonlinear stiffness can achieve the least buffer coefficient among the three leg mechanisms. This paper lays a theoretical groundwork for the rapid walking and control of walking robots.

Key words: leg mechanism, piecewise nonlinear stiffness, buffer coefficient, walking robot

摘要：

针对隔离着地冲击的需要，为步行机器人设计了一种由连杆、线性拉伸弹簧和线性阻尼器构成的被动缓冲型腿机构，根据该机构的几何关系导出其等效刚度，并且给出了机构个别参数对刚度的影响。利用数据拟合将该等效刚度分段表示为三次非线性刚度和线性刚度；然后利用数值方法得到了缓冲过程的位移响应和加速度响应；最后分别比较了具有分段非线性刚度、三次非线性刚度和线性刚度的腿机构缓冲系数。结果表明，在最优阻尼比的情况下，具有分段非线性刚度的腿机构能够获得最小的缓冲系数，从而为实现步行机器人的快速步行和控制提供了理论依据。

关键词: 腿机构；分段非线性刚度；缓冲系数；步行机器人