A Fast Calibration Method for 3D Printing Robot Based on Distance Constraint

Aiming at the difficulty of tool center point (TCP) calibration of 3D printing robots, a fast calibration method is proposed. Firstly, the kinematics model of the robot is obtained according to the D-H parameters. Secondly, the coordinate system transformation model is established by using the positional relationship between the laser tracker and the robot. Thirdly, the position of the TCP relative to the measurement coordinate system is read by the laser tracker, and the position of the TCP relative to the base coordinate system is calculated by the kinematics model of the robot. Finally, the TCP is calculated using the distance constraint. In order to verify the effect of the method, a 3D printing experiment for repair of bone defect is carried out. In the experiment, the alginate hydrogel is used as the bio-ink, and the trajectory planning is performed by parametric method. Then, the EinScan-Pro is used to scan the printing effect. By comparing the scanned 3D models, its results demonstrate that the proposed method performs better than the traditional calibration method. With this method, the average error and standard deviation of the printing surface can be reduced by 49% and 13%, respectively, which effectively improves the processing quality of the traditional method.