A Fuzzy System for VSI X-Bar Control Chart

Abstract—Statistical quality control charts are widely used in monitoring production process. In this study, a fuzzy control chart with variable sampling interval (VSI) is proposed by combining Fuzzy set theory and VSI method to improve the efficiency of detecting a signal. A fuzzy control chart is constructed using the output value of fuzzy logic approach for process monitoring. The VSI method is then applied for the fuzzy control chart to reduce the time for detecting the out of control signal. The simulation results show that the performance of the proposed fuzzy control chart with VSI in detecting the shift of process average, variation and trend is better than that of the traditional X control chart or VSI X control chart.