Methodology for analyzing the dependencies between human operators in digital control systems

Abstract

In a digital control system, the dependency model between the actions of operators differs from that in a conventional control room because information sharing and the main control room (MCR) operations are team operations. Dependencies between the actions of operators are more common in a digital control system compared with a conventional control room because operators share the same information and MCR operations are directed by team decisions. Therefore, assessing the dependencies between operators is an important aspect of human reliability analysis. In this study, we use a fuzzy logic-based approach to evaluate the dependencies among the actions of operators in the present study. First, the factors that influence the dependency levels among the actions of operators are identified by analyzing the characteristic human factors in a digital control system and an analytical model of the dependencies is then constructed. Second, a method for analyzing the dependencies between the actions of operators is established based on a fuzzy logic approach. This method can simulate vague and uncertain knowledge, but it also provides a clear explanation of the origins of results and their reasoning process by tracing the steps in reasoning. Therefore, traceability and repeatability are characteristics of the proposed method. Third, we present a case study to demonstrate the proposed approach. Finally, we demonstrate that the results obtained are reasonable and that the established model is stable based on validations that involve data comparisons and a sensitivity analysis of the model.