Structured logic control in glass preparation processes

Experience with the development and operation of process controls using modern control theory is compared to experience with reasoning-based control formatted in structured logic. The discussion is based on recent results on controls used in the preparation of molten glass for the manufacture of glass articles. The general aspects of the temperature controller for the gas burner forehearth are presented. The limitations of using PID (proportional integral derivative) control in reducing upstream disturbances are discussed as well as the implementation of a feedforward-feedback algorithm based on a stochastic parameter-identification method. Because of the sensitivity of the stochastic algorithm to operational variations of the forehearth, it is less satisfactory to use, given the current conditions prevalent on production plant floors. Preliminary results are presented for an application of fuzzy logic in the forehearth temperature process.<>