Fuzzy theory and quality control charts

Quality control charts are one of the most important tools of statistical process control, used to analyze the behavior of different processes and to predict possible production failures. The use of a fuzzy approach in the design of control charts has allowed to improve the performance of traditional charts, as well as to be possible of a simple approach for the design of control charts for linguistic variables with multinomial distribution for both, the univariate case as for the multivariate case. In this paper we will show some of the main proposals of fuzzy control charts found in the literature.