基于函数性数据分析的数控机床瞬时可用度建模

借助于函数性数据分析方法,提出了一种求解数控机床瞬时可用度方法。首先以四次Bernstein多项式为基函数对可靠度估计值进行平滑,并采用最小二乘法估计基函数拟合参数。其次,对维修度估计值按照故障发生时间截面进行跨截面套准,按维修度套准后的变化趋势,选择傅里叶基函数对其进行平滑处理,并采用非线性最小方差法求解拟合系数。最后,通过构建基于函数性线性回归模型建立了数控机床瞬时可用度模型,并以18台加工中心为实例进行分析。实例分析表明,该建模方法瞬时可用度拟合相关系数达到0.9641,能有效地对数控机床的瞬时可用度进行评估。

Instantaneous availability modelling of CNC machine tool based on functional data analysis

A new way to calculate the instantaneous availability of the computer numerical control(CNC) machine tool was proposed based on the functional data analysis method.Using the quartic Bernstein polynomial as basis function to smooth the reliability estimation values,as well as the least square method to estimate the fitting parameters of the basis function.The estimated maintainability was across-section adjusted according to the trouble occurrence time section.Based on the adjusted trend of maintainability,the Fourier basis function was chosen to smooth it.The fitting coefficients were solved by the non-linear least variance method.A model was built for the instantaneous availability of the CNC machine tool based on the functional linear regression model,and taking 18 machine centers as examples to verify the proposed model.The results showed that the proposed model gave out the correlation coefficient of 0.9641,being effective to evaluate the instantaneous availability of the CNC machine tool.