Geometric error identification method for machine tools based on the spatial body diagonal error model

For the identification of the geometric error in the CNC machine tools, this paper proposes a geometric error identification method for machine tools based on the spatial body diagonal error model. A body diagonal error measurement method is proposed to obtain the spatial error, which avoids repeated installation errors. In order to address the pathological problem in geometric error identification, a two-step regularization method based on the spatial body diagonal error model is proposed. Firstly, the mapping relationship between the geometric error of the machine tools and the spatial body diagonal error, which is measured by a multibeam laser interferometer, is established. Secondly, a two-step regularization method is adopted to improve the identification accuracy and the stability. Finally, the body diagonal error measurement method is applied to a horizontal three-axis machining center, and the measurement results show that the method is feasible. Simulations and experiments are performed to compare the two-step regularized identification method with the least square identification method, and the results prove the good reliability and validity of the proposed method. Comparing the identification results with the measurement results, the absolute error is less than 4.8584 mu m, and the relative error is less than 25.6062%. It shows that the spatial body diagonal error model proposed in this paper is comprehensive, and the geometric error identification method is systematic and universal.