Stiffness Estimation of a 2-DoF Parallel Kinematic Machine

This paper presents stiffness of 2-degrees of freedom Parallel Kinematic Machine (PKM). The behavior of PKM is an isotropic, and depends on the tool position within the workspace. It is highly essential to study the variation of stiffness within the workspace as it affects the machining performance. The kinematic and kinetostatic modeling of a planar, two-degree of freedom, generic PKM with prismatic actuator (carriage) has been carried out. Stiffness variation in workspace was studied. Modeling of PKM was done in CAD software and stiffness was estimated by using ANSYS software. The Stiffness was also estimated by formulating a model of each substructure by using empirical equations based on inverse kinematic equations. Finally, a comparison is made between the stiffness obtained by FEM model and the empirical model. The study shows the effect of tool position within the workspace upon stiffness of the PKM.