Advanced calibration applied to a collaborative robot

Abstract

Geometric calibration improves the accuracy of an industrial robot by adjusting its geometric parameters. Joints compliance is another cause of poor accuracy in serial robots. To overcome this problem, joints compliance and applied torques on each joint must be known. The classic method consists in estimating the joints torque with a resolution technique such as the Newton-Euler algorithm and a mass model. The quality of such an estimation relies on the quality of the mass model, which is often poorly known. By contrast, this paper presents a calibration process with online position error correction adapted for a collaborative robot LBR iiwa Kuka robot with embedded joints torque sensors.