Calibration of geometric and non-geometric errors of an industrial robot

Inaccurate positioning of the robot end effector causes joint deformation a s well as geometric errors when an industrial robot has a payload at its en d effector. We propose a new approach of calibration which deals with joint angle dependent errors to compensate for these phenomena. To implement thi s method, we divided the robot workspace into several local regions, and bu ilt a calibration equation by generating the constraint conditions of the e nd effector's motion in each local region using a three-dimensional positio n measurement system. The parameter errors obtained this way were interpola ted using the Radial Basis Function Network (RBFN) so as to estimate calibr ation errors in the regions that we did not measure. We used this technique to improve the performance of a six DOF industrial robot used for are weld ing.