Static Positioning Accurarcy of a Redundant Robotic System

Many applications in the field of robotics require a high positioning accuracy of the robot end-effector. This accuracy strongly depends on the resolution of the position sensors and on manufacturing tolerances of the machine like length errors or misalignment of axes (geometric error parameters). With a static calibration process, these error parameters can be obtained by least squares error minimization. The least squares solution depends on the choice of the robots poses that are chosen for the calibration process. These poses are optimized with a special selection algorithm. The calibration, including the calculation of the optimal poses is discussed for a seven-axes redundant robot. Special emphasis is laid on the dependency of the geometric parameters on temperature changes and on absolute position errors due to temperature changes.