MOHAMMAD HASSAN FAZEL ZARANDI - DEPARTMENT OF INDUSTRIAL ENGINEERING, AMIRKABIR UNIVERSITY OF TECHNOLOGY, TEHRAN, IRAN
ISMAIL BURHAN TURKSEN - DEPARTMENT OF MECHANICAL AND INDUSTRIAL ENGINEERING, UNIVERSITY OF TORONTO, TORONTO, ON, CANADA, M۵S۲H۸
ALI HUSSEINIZADEH KASHAN - DEPARTMENT OF INDUSTRIAL ENGINEERING, AMIRKABIR UNIVERSITY OF TECHNOLOGY, P. O. BOX: ۱۵۸۷۵-۴۴۱۳, TEHRAN, IRAN

This paper addresses the design of control charts for both variable ( x chart) andattribute (u and c charts) quality characteristics, when there is uncertainty about the processparameters or sample data. Derived control charts are more flexible than the strict crisp case, dueto the ability of encompassing the effects of vagueness in form of the degree of expert’spresumption. We extend the use of proposed fuzzy control charts in case of linguistic data using adeveloped defuzzifier index, which is based on the metric distance between fuzzy sets.

Process control, Control chart, Quality characteristics, Fuzzy numbers