Process Improvement in Feedback Adjustment

Process adjustment, also called engineering process control(EPC), is applied to maintain process output close to a target value by manipulating controllable variables, but special causes may still make the process deviate from the target and result in significant costs. Thus, it is important to detect and mediate deviations as early as possible. We propose a one-step detection method, the moving search block(MSB), with which the time and type of a special cause can be identified in short periods. A modified control rule that can entertain the effects of the special cause is proposed. A numerical example is presented to evaluate the performance of the proposed scheme.

[1]  Kwok-Leung Tsui,et al.  A mean-shift pattern study on integration of SPC and APC for process monitoring , 1999 .

[2]  Fugee Tsung,et al.  Joint Monitoring of PID-Controlled Processes , 1999 .

[3]  Herbert Moskowitz,et al.  Run-Length Distributions of Special-Cause Control Charts for Correlated Processes , 1994 .

[4]  Chinmo Roan,et al.  CHANGE PATTERNS OF TIME SERIES-BASED CONTROL CHARTS , 1996 .

[5]  Lon-Mu Liu,et al.  Forecasting time series with outliers , 1993 .

[6]  David E. Booth,et al.  Joint Estimation: SPC Method for Short-Run Autocorrelated Data , 2001 .

[7]  S. A. Vander Wiel,et al.  Monitoring processes that wander using integrated moving average models , 1996 .

[8]  Daniel W. Apley,et al.  The dynamic T2 chart for monitoring feedback-controlled processes , 2002 .

[9]  B. W. Ang,et al.  A SPC Procedure for Detecting Level Shifts of Autocorrelated Processes , 1998 .

[10]  W. T. Tucker,et al.  Algorithmic statistical process control: concepts and an application , 1992 .

[11]  Daniel W. Apley,et al.  The dynamic T 2 chart for monitoring feedback-controlled processes , 2002 .

[12]  George E. P. Box,et al.  Statistical process monitoring and feedback adjustment: a discussion , 1992 .

[13]  George E. P. Box,et al.  [Statistical Process Monitoring and Feedback Adjustment]: Response , 1992 .

[14]  Herbert Moskowitz,et al.  [Run-Length Distributions of Special-Cause Control Charts for Correlated Processes]: Rejoinder , 1994 .

[15]  R. Tsay.  Time Series Model Specification in the Presence of Outliers , 1986 .

[16]  W. T. Tucker,et al.  Algorithmic Statistical Process Control: An Elaboration , 1993 .

[17]  Wei Jiang,et al.  SPC Monitoring of MMSE- and Pi-Controlled Processes , 2002 .