| Control chart is an important tool of statistical process control.With the continuous development of science and technology and productivity,the application of control chart has gradually expanded from monitoring single quality characteristics to monitoring multiple quality characteristics.At the same time,in the field of chemical industry,metallurgy and other production,the quality of products is not only affected by many factors,but also has the autocorrelation phenomenon.Therefore,the study of multivariate autocorrelation control chart is very important.In the actual production process,the phenomenon of small fluctuation deviation is common.The conventional Shewhart control chart is only suitable for monitoring the large fluctuation process,while the MEWMA control chart has good monitoring effect for the small fluctuation deviation of the process.In the design of control chart,the monitoring efficiency of control chart can be improved by dynamic design,and the operation cost of process can be reduced by economic design.Therefore,this paper studies the economic design of dynamic residual MEWMA control chart,and the main contents is:(1)Variable sampling interval(VSI),variable sample size(VSS),variable sampling interval(VSSI)and variable sample size(VSSI)were designed for residual MEWMA control chart;On the basis of Lorenzen & Vance economic model,through the corresponding improvement,the economic design of three kinds of dynamic control charts is carried out.Combined with the actual example,the genetic algorithm is used to solve the model.(2)This paper studies the calculation of three evaluation indexes of dynamic control chart.According to different dynamic control charts,the average alarm time,the average number of samples and the average number of observations are calculated by Monte Carlo simulation.(3)The sensitivity analysis of the economic models of three kinds of dynamic control charts is carried out.Through orthogonal test and regression analysis,the correlation between the design parameters of three kinds of control charts and the economic model parameters is studied,so as to provide theoretical basis for the parameter setting of control charts in the process of practical application.(4)The economic design results of three kinds of dynamic control charts are compared.By comparing the economic design results of three control charts in the same orthogonal experimental environment,it is verified that the economic design results of VSSI residual MEWMA control chart are optimal among the three control charts.Through dynamic design and economic design,the monitoring efficiency of residual MEWMA control chart is improved and the operation cost of control chart is reduced;Through sensitivity analysis,the relationship between the design parameters of the control chart and the parameters of the economic model is obtained,which can provide a theoretical basis for the parameter selection of the control chart in practical application. |
