Optimization of Condition Monitoring Decision Making by the Criterion of Minimum Entropy

Abstract

Condition-based maintenance (CBM) is a promising technique for a wide variety of deteriorating systems. Condition-based maintenance’s effectiveness largely depends on the quality of condition monitoring. The majority of CBM mathematical models consider perfect inspections, in which the system condition is assumed to be determined error-free. This article presents a mathematical model of CBM with imperfect condition monitoring conducted at discrete times. Mathematical expressions were derived for evaluating the probabilities of correct and incorrect decisions when monitoring the system condition at a scheduled time. Further, these probabilities were incorporated into the equation of the Shannon entropy. The problem of determining the optimal preventive maintenance threshold at each inspection time by the criterion of the minimum of Shannon entropy was formulated. For the first time, the article showed that Shannon’s entropy is a convex function of the preventive maintenance threshold for each moment of condition monitoring. It was also shown that the probabilities of correct and incorrect decisions depend on the time and parameters of the degradation model. Numerical calculations show that the proposed approach to determining the optimal preventive maintenance threshold can significantly reduce uncertainty when deciding on the condition of the monitoring object.

Classification of Systems and Maintenance Models

“…The maintenance effectiveness indicator was the expected cost per regeneration cycle. Studies [53,54] have shown that the probabilities of imperfect inspections at condition-based and predictive maintenance are functions of the degradation model parameters and strongly depend on time. In the study [55], the case of imperfect testing of the crack depth in a fighter wing was considered.…”

Optimization of Maintenance Task Interval of Aircraft Systems

“…There is currently an increased research interest in aircraft maintenance optimization since it directly impacts system availability and operational costs [42]. The main aircraft maintenance optimization techniques that have been researched recently are based on aircraft maintenance service scheduling, spare parts inventory, and aircraft maintenance planning.…”