A New Method of Monitoring Process Disturbance Based on Integrated SPC/EPC

摘要

Special reason and common reason bring on the process disturbance. Statistical process control (SPC) is commonly used to monitor the process disturbance which arises from assignable reason. Engineering process control (EPC) compensates the deviation of output for common reason based on the feedback adjustment principle. Therefore, integrated SPC/EPC approach has better performance than that merely using SPC or EPC. However, in practice, it is very hard to search the appropriate method to apply for integration of SPC/EPC. The main reason is that EPC's compensation has depressed probability which assignable reason is monitored by control chart. In this paper, a joint-monitoring method is designed to account for the above problems through detecting process output as well as monitoring process input. An example is given to prove that joint-monitoring can detect the process disturbance more quickly and more accurately.