Novel Online Re-Calibration Method for Multi-Axis Force/Torque Sensor of ITER Welding/Machining Robot

This paper proposes a new method for re-calibration of multi-axis force/torque sensors. The method makes several improvements to traditional methods. It can be used without dismantling the sensor from its application and requires a smaller number of standard loads for calibration. It is also cheaper and faster method in comparison with traditional calibration methods. The method was developed in response to re-calibration issues with the force sensor used in the welding/machining robot of the international thermonuclear experimental reactor (ITER) vacuum vessel (VV) and the approach aimed to avoid dismantling and on-site assembly of components of the ITER robot. A major complication with the ITER robot is difficult to access the robot when it operates inside the VV; especially after the first plasma, which will make the vessel radioactive. The proposed technique is based on the design of experiment methodology. It has been successfully applied to different force/torque sensors and this paper presents experimental results for the use of the calibration method with the force sensor that would be used on the ITER robot.