在生產過程中由於受到可歸屬原因之影響,產品品質特性數據可能產生平 均值及/或變異數之改變。這些變化都代表著製程是處於管制外(異常)之 狀態。在統計製程管制中,當管制對象為個別值時,通常是以個別值及移 動全距管制圖來監視製程之變化。過去之研究結果說明此兩種管制程序並 無法區分製程之異常是來自於平均值改變、變異數改變或兩者同時產生變 化。本研究是以類神經網路(artificial neural networks)為基礎發展一 辨認製程異常之程序。我們所考慮之製程異常類型有(1) 製程平均值變 化 (向上或向下移動);(2)變異數變化;(3)製程平均值和變異數同時變 化之情形。類神經網路之成效是以蒙地卡羅模擬法產生數據來評估,並與 其它管制法比較。本研究所採用之評估比較指標為平均連串長度和正確辨 認率。本論文所提出之異常類型辨認系統較傳統之管制圖及已發表過之類 神經網路辨認系統,除了有更快的偵測速度及較高之正確辨認率外,更提 昇了系統整體的穩定性及即時、連線的可行性。
The combined individual measurements and moving range charts are often used in statistical process control to monitor a series of individual measurements coming from a manufacturing process. Previous research has shown that these charts are not effective in identifying the process change caused by a shift in mean or in variability or both. In this research, a set of pattern recognizeres based on artificial neural network techniques have been developed as an alternative means to traditional methods. The out-of-control conditions considered in this research includes the following: (1) a shift in the process mean; (2) a change in the process variability; (3) a shift in the mean as well as the variability. The performance of the proposed neural networks has been evaluated based on the average run length (ARL) and the recognition accuracy. A Monte Carlo simulation has shown that the proposed neural network approach out performs other traditional methods in terms of recognition accuracy.