Multi-point calibration method for articulated arm coordinate measuring machine based on an observability index

Kinematic calibration is an effective way to improve the accuracy of articulated arm coordinate measuring machine (AACMM). In this paper, a multi-point calibration method for AACMM based on observation index is proposed. First, the kinematic model is established according to the D-H method, and the measurement error model is established on the basis of the D-H model. Then, the feasibility of using the observation index to evaluate the posture of AACMM is analyzed, and simulations are carried out to verify the correlation between the level of the observation index and the quality of the calibration results. In the simulation, the influence of the number of measurement positions and the number of measurement points on the calibration results are studied in combination with the observability index, and on this basis, a multi-point calibration method is proposed. Finally, experiments are carried out to verify the superiority of the multi-point calibration method. The results show that, compared with the single point calibration method, the multi-point calibration method can improve the measurement accuracy by 31.58%, and the average measurement error of the AACMM after the multi-point calibration method is 0.0091 mm.