Monitoring of caliper sensor fouling in a board machine using self-organising maps

This paper presentes a process-monitoring scheme utilising adaptive self-organising maps (SOM) to detect process conditions that lead to the fouling of a caliper sensor in a board machine. The scheme is based on mapping on a SOM the process measurements and the calculated variables which provide insight into the chemical phenomena involved in fouling to classify faulty process conditions. The time-variant nature of the board making process was taken into account by regularly re-training the SOM. The monitoring scheme is demonstrated with industrial data, and the results are presented and discussed.