Nonlinear prediction and analysis of the precision remaining useful life of the key meta-action unit of CNC machine tools with incomplete maintenance

Abstract

The accuracy of the PRUL (precision remaining useful life) prediction is of great significance for the accuracy of active maintenance of CNC (computer numerical control) machine tools. KMAU (key meta-action unit) is the meta-action unit that has a significant impact on the quality characteristics of CNC machine tools. Therefore, it is taken as the research object, and a new method for predicting the PRUL is proposed. Firstly, considering the nonlinearity and uncertainty of the KMAU precision degradation process, the nonlinear Wiener process is used to establish its precision degradation model, and the model parameters are updated online by Bayesian principle. Secondly, the precision of the KMAU will be partially restored under the incomplete maintenance, and the composite NHPP (non-homogeneous Poisson process) is improved by GPIM (generalized proportional intensity model) to describe the change of KMAU's precision. Then, the precision comprehensive degradation model of the KMAU is built by combining the nonlinear Wiener degradation model. Finally, the maximum likelihood estimation method is used to estimate the parameters of the proposed model, and the PDF (probability density function) of the PRUL of CNC machine tool KMAU is obtained according to the time that the precision degradation first reaches its failure threshold (called the first arrival time), so as to predict the PRUL of the KMAU. The method proposed in this paper comprehensively considers the impact of nonlinearity, uncertainty, and incomplete maintenance on the accuracy of PRUL prediction for CNC machine tools, and has high accuracy. The KMAU of CNC machine tool turntables made in China is taken as an example, and the correctness, rationality, and superiority of the proposed method are verified by multiple method comparisons and experimental.