Stiffness Matrix Analysis of Six-Revolute Serial Manipulator

This paper presents a simple procedure that can be used to determine the stiffness matrix of 6R serial manipulator in selected points of the work space with joint stiffness coefficients taking into account. Elastokinematical model for the robot manipulator FANUC S-420F was considered as spatial and serial kinematical chain composed of six rigid links, connected by ideal revolute joint (without clearances and deformable elements), with torsion elasticity of the joint drive system (relative torsion deformations are proportional to acted torques) taking into account. Assumed model is used for displacement analysis of the end-effector for a given applied force in quasi-static condition. The analysis results are presented as Cartesian stiffness matrix of studied manipulator.