A 6-DOF articulated robot stiffness research

Weak stiffness and insufficient kinematic accuracy of industrial robot obstruct its application in precision machining. Before enhancing machining accuracy by introducing stiffness compensation model, the influence of robot weak stiffness on machining accuracy should be identified. This paper presents an evaluation on the spatial stiffness behavior of end effector by varying joint angles. The coupling relationship between joint stiffness and Cartesian stiffness is first generalized. Based on the calculation on joint stiffness values, simulations focused on the spatial behavior of end effector stiffness are then performed. Simulation results indicate that dramatically stiffness mutations of end effector occur in some spatial position.