A hierarchical strategy for the temperature control of a hot strip roughing process

An on-line strategy to control the slab temperature in a hot steel roughing process is described. The strategy uses a hierarchical structure to reduce the dimensionality of the problem. The resulting controller is attractively simple, requires only a small amount of computer time and has adaptive features. The strategy has been applied to the control of a detailed digital computer simulation of a continuous roughing process and the results show that the controlled variables, slab thickness and temperature remain very close to the desired values despite fluctuations in the hardness, water descaling flow rates and furnace release temperature. These desired values are either determined from present process operation, or are computed from the process equations by hill-climbing on the stand output thicknesses. The hill-climb is done off-line using a maximum gradient method.