Gráficos de controle: aspectos teóricos e práticos a partir da lógica formal e da lógica fuzzy

Many processes are analyzed from vague or imprecise information. It is important to find strategies that enable the analysis and interpretation of such data. This article presents a strategy for building fuzzy control charts, involving a method for transforming crisp values into fuzzy values and a method for ordering fuzzy numbers. The charts obtained are compared with the traditional Shewhart control charts in a context of inaccurate: the study of some sensory characteristics of a product in a food industry (color, aroma, texture, taste and acidity). It was found that the fuzzy control charts showed more flexibility, with the creation of internal and external warning areas. They are less rigorous in evaluating the central tendency and a little more rigorous in assessing the variability.