Reliability Modelling Method for Phased Mission System Considering Multi-Phase Continuous Backup Strategy

To achieve high reliability of the phased mission system (PMS), the phase backup strategy is always designed except for the redundant components. In the traditional phase backup strategy, only one phase is backed up at a time. However, in some PMS, continuous backup of multiple phases will occur, that is, if a task in a certain phase of the system fails, the system will go back to one or more phases prior to this phase, and re-execute these tasks in sequence. For this problem, a reliability modelling method of PMS considering multi-phase continuous backup strategy is proposed in this paper. Firstly, the subsystem composition of a UAV and its mission phases under multi-phase continuous backup strategy are analyzed. Secondly, a new model based on binary decision diagram model for phased mission system (PMS-BDD) is developed to model the mission reliability of the UAV considering multi-phase continuous backup strategy. Thirdly, according to the accelerated failure model and Poisson process, the analytical expression of mission reliability of the UAV in the case of random shock is derived. Finally, a case study on a UAV's reconnaissance strike mission is used to validate the proposed method.