Robot calibration and compensation

A method is presented for calibrating and compensating for the kinematic errors in robot manipulators. A method of selecting a set of independent kinematic errors for modeling any geometric errors in a manipulator´s structure is developed. A calibration algorithm is presented for finding the values of these kinematic errors by measuring the end-effector position. These kinematic errors are experimentally determined for a PUMA 560 six-joint manipulator. Two general-purpose compensation algorithms are developed and the improvement in the Cartesian position of the end-effector is experimentally measured and these results are presented. The results show that the positioning accuracy of a robot manipulator can be substantially improved using a relatively simple technique for measuring the Cartesian position of a tool attached to the end of the manipulator