Hierarchical process control by combining SPC and soft computing methods

Statistical process control (SPC) provides methods of monitoring a system to improve the quality of the product. However, using SPC alone has limitations since it does not control a system but rather monitors it to remove the root causes. SPC and feedback control are combined in a hierarchical structure to monitor a system and use the information to compensate for deviations of the output of a system. Most industrial systems are composed of several constituent subsystems that are coupled. Large-scale system (LSS) theory and hierarchical control structure are used to not only optimize the recipe for the individual subsystems but also to optimize for the entire system. The proposed algorithm will be implemented in the controlled atmosphere brazing (CAB) furnace to braze aluminum heat exchange components