Accuracy improvement of a 3D passive laser tracker for the calibration of industrial robots

•Propose a 3D passive laser tracker (3DPLT) for the accuracy calibration of industrial robots.•Derive the spatial position error modeling of the 3DPLT system.•Identify error parameters through experiments.•Verify the compensated spatial error of 3DPLT by CMM in multi-posture and large-rang.•Verify the applicability of the 3DPLT through preliminary tests of an industrial robot. The laser tracker has been used as the mainstream instrument for the position accuracy calibration of industrial robots for quite a long time. However, due to the complexity of the built-in dual-axis active servo tracking system, its cost is high and the target reflector has to adjust its pose frequently, so it cannot be popularized in the production and application sites of industrial robots. Based on this drawback, a 3D passive laser tracker (3DPLT) with high precision, simple structure, easy operation and low cost is proposed in this paper. Firstly, the overall structure of the system is designed, and its position error model based on the principle of spherical coordinate measurement and vector transfer method is established. Then, the error parameters are identified by experiments to formulate the error compensation model. Finally, the multi-pose and large-range spatial error compensation verification experiments of the system are carried out on a commercial coordinate measuring machine. The results show that the spatial volumetric errors of the 3DPLT can achieve within 40 μm after compensation with a good repeatability of ±4 μm. A comparison contouring test with a commercial ballbar is also carried out to validate its applicability of robot calibration.