There are two possible approaches. One option is to design rules for all possible combinations of input variables. The alternative is to design rules for all possible output combinations. Which choice is easier depends on the relative number of controlled AND manipulated variables. Feedforward variables also must be counted as input variables.
However, depending on interaction
s in the process, it may not make sense to address all possible combinations. Not all variables need to be considered together, and the set of all logical combinations can usually be broken down into more appropriate subsets.
Process interactions: Problems created by process interactions still exist. When interactions exist and have significant impact on the process, the logic of the rule set structure should accommodate the need to take coordinated actions that decouple the process responses.
This installment has presented the most basic concepts of fuzzy logic control. In the next installment in this series, these concepts will be applied to the specific problem of reactor control.
