Many industrial processes are difficult to control because the product
quality cannot be measured rapidly and reliably. One solution to this
problem is inferential control, which uses an inferential estimator t
o infer unmeasurable process outputs from secondary measurements, and
controls these outputs. This contribution proposes a new approach for
designing a Fuzzy Neural-Net (FNN)-based inferential estimator. The FN
N is constructed by distributed multi-networks, whose classification,
online running and learning are based upon fuzzy set theory. Applicati
on of this method to an industrial high purity distillation column sho
ws that the FNN-based inferential control is far superior to conventio
nal composition control.