Abstract
•A system with limited resource determining maximum operation time is considered.•During the mission the system can undergo several maintenance actions.•Algorithm for determining expected mission downtime is suggested.•Operation and maintenance schedule minimizing the expected downtime is obtained.
Traditional reliability models typically assume that a system can operate until it is failed or not needed due to the mission completion. In practice, the system may have limited resource (e.g., battery power, fuel) and thus have certain maximum operation time due to the resource depletion. This paper makes contributions by modeling and optimizing the expected mission downtime (EMD) for a resource-constrained system that requires replenishing the resource according to a pre-specified operation and maintenance schedule (OMS) for accomplishing a mission of certain duration. Different types of maintenance options characterized by different maintenance durations, efficiencies in reducing the system's cumulative exposure time, and resource replenishing amounts are considered. Based on a new numerical method suggested for the EMD evaluation, the optimal OMS problem is formulated and solved minimizing the EMD. A detailed case study on an unmanned aerial vehicle performing a surveillance mission is conducted to investigate the influence of several system parameters on the EMD and optimization solutions, including the maximum amount of resource, system reliability, resource consumption during system activation and operation, resource replenishment speed, as well as maintenance duration, efficiency, and failure probability.