Non parametric on-line control of batch processes based on STATIS and clustering

Résumé

Batch processes are widely used in several industrial sectors, e.g. food and pharmaceutical manufacturing. Process performance is described by variables which are monitored as the batch progresses. Data arising from such processes are usually monitored using control charts based on multiway principal components analysis. In this paper we propose a non parametric quality control strategy for monitoring batch processes with fixed as well as variable duration. In our proposition, data sets associated to batches are reduced using the STATIS method. Monitoring of batch performance is accomplished directly on principal plane graphs, from which non-parametric control regions are derived through convex hull peeling. This general approach allows off-line monitoring of batch processes as well as on-line monitoring after a constrained clustering step based on multivariate extension of W.D. Fisher's algorithm is carried out. A real example of batch process with fixed duration illustrates the proposed method.