五自由度并联机械腿静力学性能评价与优化设计

Static performance evaluation and optimal design of 5-DOF parallel mechanical leg

为了对一种六足机器人的五自由度并联机械腿进行静力学性能评价和优化设计,提出了一种同时考虑约束力映射关系和驱动力映射关系的腿部机构静力学分析方法,并基于此方法对机械腿进行了优化设计。首先,通过分析腿部机构的驱动、约束映射关系,分别建立了腿部机构的驱动雅可比矩阵和约束雅可比矩阵;应用虚功原理建立了腿部机构的驱动静力传递平衡方程,在定义驱动静力学评价指标的基础上绘制了评价指标分布图,得出了结构参数与驱动静力评价指标之间的关系曲线。然后,采用同样的方法建立了腿部机构的约束静力传递平衡方程,定义了约束静力学性能评价指标,得出了结构参数与约束静力评价指标之间的关系曲线。最后,基于驱动、约束静力学性能评价指标,采用蒙特卡罗法对结构参数进行了优化设计。计算表明,固定平台结构参数a为200mm、运动平台结构参数b为80mm,UPU支链长度l1min、l1max分别为500mm、900mm时,腿部机构的静力学综合性能最好。

To evaluate the static performance and design optimally a parallel mechanical leg for the six legged robot, a static analysis method based on the mapping of both constraint and actuation forces was proposed,and the mechanical leg was designed based on this method. Firstly, the constraint and actuation Jacobian matrixes were established based on the mapping of both constraint and actuation. Then, according to the virtual work principle, the actuation statics transmission equation was estab lished, the performance evaluation indexes of actuation statics were designed, and the relationship curve between the performance evaluation index and structure parameters was calculated. By the same way, the transmission equation and performance evaluation index of constraint statics were obtained, and the relationship curve between the performance evaluation index and structure parameters was al so calculated. Finally, based on the performance evaluation indexes both of constraint and actuationstatics, the structure parameters were optimally designed by Monte Carlo method. Calculations show that when the structure parameters of a fixed platform and a movement platform are 200 ram,and 80 mm and the UPU branched chain lengths llmin llmax are 500 mm and 900 mm, the statics comprehensive performance of the parallel mechanical leg is the best. These studies lays the theoretical foundation for further study of the six-legged robot.