Reliability computation of systems with latent-failures and monitoring

Component redundancy is used to improve reliability and to postpone maintenance in many system operations. In such system, a failure of a component may occur and the system may still be used in operation. Thus the system dispatch state may not be a fully-operational state. Some subsystems may employ monitoring to determine if a unit is operational or not at the beginning of a mission. Redundant components may be checked and repaired at the end of periodic intervals, called maintenance check times, to reduce the cost of maintenance. In such scheduled maintenance (SM) systems, one may be interested in determining the mission reliability for a particular mission. We, in this paper, present analytic techniques to compute the reliability of a mission based on this maintenance scenario. Our model predicts accurate reliability values in a variety of scenarios. We also compare our solution with most used “back-of-envelope” computation methods and show shortcomings of those approaches. Several examples are shown and we validate our results using tools HARP, HARP-PMS, HARP-SMS, and EHARP