In order to control an apparatus, such as a rolling mill, a control device may use a pre-set operation pattern to generate a pre-set command signal, which is then modified. That first modification may be part of a feedback loop in dependence on the variation of a variable operation device of the apparatus, on a plurality of pre-set signals may be combined by fuzzy logic. Then the relationship between the modified pre-set command signal and the variation of the variable operation device is investigated to generate a compensation signal which is used to modify further the pre-set command signal. In a feedback loop, that further modification may compensate for changes in the operating point of the loop, due to changes in the apparatus being controlled. In a fuzzy logic arrangement, the compensation signal may be a further control pattern developed by the control device itself, which is combined with the pre-set patterns by fuzzy logic. The control device may be in the form of a series of modules.