关键词: 统计过程控制, 指数加权移动平均控制图, 优化模型, 质量损失, 过程均值偏移

Abstract: Aiming at the circumstance of stochastic process mean shift,a statistical-economic design method of EWMA control chart was proposed.In this method,the three phases of the in-control condition,the out-of-control condition without signal and the maintenance condition to restore were defined as a cycle to analyze the average time and the quality cost structure of the three phases.The quality losses caused by the defective products were quantified by computing the probability that the product quality characteristic fell beyond the specification limit.The optimal design model of EWMA control chart was set up to minimize the expected cost per time unit,and the genetic algorithm was designed to obtain the optimal EWMA control chart parameters such as the sample size,the sampling interval,the smoothing factor and the control limit of the chart.A number of comparative experiments were conducted to show that the proposed model was superior to the Shewhart X control chart and the traditional EWMA control chart.

Key words: statistical process control, exponentially weighted moving average, optimization model, quality loss, process mean shift