绳驱动仿腕关节绳拉力分布和可控刚度特性分析

为模拟人臂腕关节的结构功能,提出了有别于传统仿生关节的3自由度绳驱动并联结构,即通过球副连接动平台与静平台实现腕关节的转动功能。考虑绳驱动的冗余特性和绳索的单向受力性,对机构的位姿结构进行静力学分析,获得绳索张力表达式,同时建立绳张力分布优化模型,通过遗传算法得到绳拉力分布情况。通过建立运动学和静力学方程对机构进行受力分析,并引入线矢量和微分变换的方式,推导出机构的固有刚度和可控刚度,建立了腕关节静态位姿结构刚度模型,并给出刚度评价指标。分析绳索张力与机构刚度的关系和可控刚度对整体刚度的影响,数值仿真分析得出腕关节机构的位姿结构刚度在工作空间中的分布规律。

Characteristics Analysis of Controllable Stiffness and Tension Distribution for a Cable-Driven Humanoid Wrist

To imitate the structure and function of human wrist,a 3-DOF(degree-of-freedom)cable-driven humanoid wrist is put forward.Its function is achieved by a ball joint which connects the moving base platform and the base.Taking into account the redundant actuation and single-direction force for the cables,the cables tension expression was obtained by static analysis.At the same time,the cable tension distribution optimization model was established,and the cable tension distribution was obtained by genetic algorithm.The wrist kinematics and statics equations were used for the force analysis,and static stiffness model including controllable stiffness and inherent stiffness was derived by introducing a line vector and a differential transform.Simultaneously,several stiffness evaluation indicators were given.The relationship between cable tension and wrist stiffness,and the influence of controllable stiffness on the overall stiffness was analysed,stiffness distribution in working space was acquired by numerical simulation analysis at the same time.