Semi-Analytical Approach for Stiffness Estimation of 3-DOF PKM

This book mainly addresses the issue of stiffness formulation of a three prismatic-revolute-spherical PKM (3-PRS PKM). Main works in this paper can be outlined as follows. By use of approaches of vector inverse position analysis of 3PRS PKM is conducted For the complex geometry shape of some components it is impossible to know their stiffness distributions with the varing configuration. Therefore ANSYS technology has to be applied to compute the stiffness coefficients of these components at different configurations. Then the computed data are used to obtain the stiffness distribution by use of the numerical fitting method. Up to now the semi-analytical stiffness model of the manipulator is completely build up and can be applied to estimate the system stiffness of 3PRS PKM. Provided with the geometry parameters and load situation on tool tip the stiffness of 3PRS PKM system is estimated based on the stiffness matrix about tool tip which is obtained by transforming the point from the center of circle composed of three S joints to the tool tip.Then the stiffness of system along x y and z directions can be solved.