Elastodynamic-model-based stiffness analysis of a 6-RSS PKM

An elastodynamic model for a 6-RSS parallel kinematic machine (PKM) is established by combining the virtual joint method (VJM) and the finite element method (FEM). According to the proposed elastodynamic model, stiffness matrix of the system is derived, based on which static stiffness of the system is analyzed. In order to validate the proposed model, finite element analysis is conducted. Results show that the proposed model is relatively accurate and can be used to evaluate rigidity of the 6-RSS PKM. Two stiffness indices are proposed for the convenience of analysis. Stiffness distributions as well as parametric analysis are conducted to offer significant guidance on the trajectory planning and structural optimization at the early design stage.