Calibration of robot DH parameters based on structured light camera

Abstract

This study presents a new calibration method using a structured-light camera for low-cost recalibration of the Denavit-Hartenberg (DH) parameters in collaborative robots. Although laser trackers provide high accuracy, they are very expensive and the procedure is complex. In contrast, structured-light cameras are inexpensive and easy to use, making them suitable for the calibration of DH parameters in collaborative robots. Experiments were conducted using the structured-light camera from ZIVID and the UR5 model from Universal Robots. The Point-to-plane Iterative Closest Point (ICP) technique was used to measure the positions of the robot base and calibration tool, and the DH parameters were adjusted using the Levenberg-Marquardt method's least-squares approach. The results showed that calibration accuracy improved with repetition, and repeated calibrations reduced the position error to an average of 1.85mm and the orientation error to an average of 0.43°. The proposed method can be usefully applied in fields where micro-level precision is not required or where automation of calibration is needed.