Design of regression model‐based automatic process control with reduced adjustment frequency

Automatic process control based on a regression model has been adopted as one of the important techniques to improve product quality in manufacturing processes. Though more frequent adjustments generally produce a superior control performance, it may also increase control cost and impair control applicability. In this paper, the concepts of quality margin and self‐compensation of noise change are introduced. Based on these concepts, a control strategy is proposed which is capable of ensuring an acceptable process performance with a reduced adjustment frequency. A case study of leaf spring forming process is conducted to compare the control performance and control adjustment frequency between the proposed approach and the existing methods. Some properties of the proposed control law are also studied. The proposed method is implemented in a hot steel rolling process to demonstrate the applicability of the proposed method.