Statistical process control on time delay feedback controlled processes

As manufacturing quality has become a decisive factor in competing in a global market, statistical process control (SPC) is becoming very popular in industries. With advances in sensing and data capture technology, large volumes of data are being routinely collected in automatic controlled processes. There is a growing need for SPC monitoring and diagnosis in these environments, SPC (statistical process control) and APC (automatic process control) can be integrated to produce an efficient tool for process variation reduction. The main goal of this article is to suggest a control chart method using to monitoring process with different time delay feedback controlled processes. A quality control model based on delay feedback controlled processes is set up. And the calculating method of average run length of control charts based on process output and control action of multiple steps delay feedback controlled processes is provided to evaluate control charts performance. A simple example is used to illustrate the procedure of this approach.