特殊复合球铰3-RPS并联机构及其连续刚度模型

采用矢量微分法研究了在大载荷作用下,兼顾支链和铰链刚度以及雅克比矩阵变化等影响因素的3-RPS并联机构完整连续刚度模型.基于螺旋理论分析了3-RPS并联机构支链及铰链构件所受作用力与机构外载荷之间的力平衡关系.采用矢量微分法分析了3-RPS并联机构动平台位姿变化与支链及铰链构件变形之间的关系.采用矢量微分法对机构的力学平衡方程进行微分,建立了完整的连续刚度模型,最后进行了数值模拟分析,结果表明并联机构刚度受载荷和位姿变化影响,简化刚度模型与完整刚度模型在工作空间边界处差值较大.

Continuous stiffness modeling of 3-RPS parallel kinematic machine with special composite spherical joints

A comprehensive continuous modeling methodology of 3-RPS parallel machine under dynamic load condition was developed and presented by considering the stiffness of legs and joints. The variational Jacobian matrix was used through vector differential and equivalent mechanism technique. Based on the screw theory, the force equation between the dynamic load on the mobile platform and its reaction forces on the legs and joints of the 3-RPS parallel machine was investigated and analyzed. The relationship between the pose (position and orientation) distortion of the mobile platform and the elastic deformation behavior of the legs and joints on 3-RPS parallel machine was established and analyzed by vector differential. A comprehensive dynamic stiffness model of the machine was developed by adding the total differential of the residual forces on the machine system. To validate the methodology, a numerical simulation was carried out. The result shows that the stiffness model of the parallel machine is affected by the outside load and the pose of the mobile platform. There is a large difference between the simple stiffness model and the integrate stiffness model near the workspace boundary of the parallel machine.