This paper discusses the controllability of paper making. We have chosen to take a broad view on the subject . With such an approach, there are four major factors that can contribute to the over-all controllability, viz. : the process with its actuators, the measurement possibilities (sensors), the information technology and, not the least, the humans involved in the paper making operation.
In the introduction to this paper, we try to put controllability in perspective . In order to make our following discussion less abstract, we then describe three cases related to controll ability in which STFI has been involved. The first deals with CD control ; the second with closed-loop quality control; the third with wet-end/retention control . Following these cases, we then discuss the four above-mentioned components that contribute to controllability and we conclude by indicating where we believe the major development needs and opportunities lie, viz. :
– we still lack essential controllability due to inadequate process design .
– new measurement possibilities are essential in order to improve the observability and thereby controllability.
– the human organization has a key role in controllability . Full automation is utopia. The operators have an increasingly difficult task. Their motivation is important .
– knowledge-based systems is an interesting area. Such systems can be of great value, but much development work is still needed .
– it is important to increase the fundamental knowledge of paper making and to establish the knowledge in such a way that it can be used for better control .