建立了基于马尔可夫链的MEWMA控制图性能分析模型,并给出了基于matlab的MEWMA控制图性能计算程序。在此基础上分析了MEWMA控制图的两个主要参数(控制限参数三和平滑系数r)对MEWMA控制图性能的影响。分析发现,对不同变量个数的多变量过程,当固定控制限L时,存在偏移δ^*。当过程偏移0〈δ〈δ^*时,r越大控制图越能更快的检出过程偏移;当过程偏移δ〉δ^*时,r越小控制图越能更快的检出过程偏移。据此对不同应用环境下MEWMA控制图参数的选择给出了相应的建议。
A model of the performance analysis on MEWMA control chart based on the Markov chain is established, and a Matlab program is designed for performance analysis. The effect of the parameters L and r( L is the control limit and r is the smoothing coefficient) on the performance of the MEWMA control chart is analyzed. The analysis results show that when L is determined there exists a point of shift δ^*. When shift of the mean 0 〈 δ 〈 δ^*, the performance of the MEWMA control chart improves with the increase in r. When shift of the mean δ 〉 δ^*, the performance of the MEWMA control chart improves with the reduction in r. The advice on the parameter selection of the MEWMA control chart is presented based on these results.