Field Kinematic Calibration of Industrial Robot Using Relative Pose Errors of the Tool Under Motion Constraint

The positioning deficiency of industrial robots is always caused by inherent kinematic errors, such as machining and assembly errors as well as the deformation and wear in the presence of long-term service. In order to calibrate robot in the confined environment of an industrial field, a kinematic calibration algorithm based on the relative pose error of the tool under motion constraint is proposed. By using the robot function of rotation around tool center point (TCP), the whole calibration process is restricted to a small measurement space and is divided into the following two stages. First, the Z-axis of joint 6 is obtained by rotating it separately, and then, the rotation parameters are identified based on the orientation error. Second, the relative position of TCP from the origin is measured, and then, the translation parameters are identified based on the relative position error. To implement the proposed algorithm, a compact R-test device worth U.S. ${\$}$ 6000 was developed to calibrate the geometric errors of Kawasaki RS010N 6-DOF robot. After calibration, the mean/maximum relative position errors are reduced from 5.0284/9.4368 to 0.54174/1.0676 mm, respectively. The verification experiment based on the absolute error model is completed by the laser tracker, and the calibration results of the two methods are compared and analyzed. The proposed method provides a theoretical basis and technical approach for the rapid calibration of robot arm in the industrial field.