Mission assignment and maintenance scheduling for multi-state systems

All military organizations depend on the reliable performance of repairable systems for the successful completion of missions. Due to limitations in maintenance resources, a maintenance manager must decide how to allocate available resources. This allocation falls within the domain of selective maintenance. The selective maintenance models considered to date treat decision-making for binary-state systems, i.e. all components, subsystems, and the system itself are assumed to be either functioning or failed at any point in time. The primary objective of this paper is to develop a modeling-based methodology for managing selective maintenance decisions when multiple (more than two) system states are possible. We define a scenario in which systems in various states of maintenance need must perform a number of different missions. For this scenario, we formulate a nonlinear mathematical program, and we explore four solution procedures for the optimization problem including use of a custom heuristic and dispatching rule as well as a commercial solver. We utilize Monte-Carlo simulation in evaluating possible mission profiles and system states. We also examine two different problem sizes, one in which an optimal solution may be obtained, and one representing a real world scenario. Our results suggest our solution methodologies are generating quality solutions for such an extremely combinatorial problem.