Individual Observation Process Monitoring Charts for Systems with Response Lags

Previously, it has been held that statistical process control (SPC) and engineering process control (EPC) were two distinct domains for process improvement. However, we design four control policies to integrate the two approaches using a proportional-integral-derivative (PID) feedback controller and Shewhart or moving centerline exponentially weighted moving average (MCEWMA) charts. We specifically consider the impact of these policies for a system with response lags modeled by a secondorder dynamic process and autocorrelated nonstationary outside disturbances. These policies are implemented using simulation and applied in a case study of a liquid-tank system. Our investigation shows this approach is effective with respect to overall system performance including quality and cost.