An extended object-oriented petri net model for mission reliability evaluation of phased-mission system with time redundancy

Abstract

Phased-mission system (PMS) has been widely used as mission reliability model of many engineering mission-critical systems. In practical, PMS can have time redundancy both inner phase and between phases, i.e. the success of one phase may only require the system to keep operational for a given time interval instead of working throughout the phase. Besides, mission task failed in one phase can be re-executed in a later phase with change of its configurations.Based on the extended object-oriented Petri net (EOOPN), this paper proposes a general modeling procedure for mission reliability evaluation of PMS, which is capable of considering the time redundancy both inner phase and between phases in relatively intuitive way. The proposed approach is performed in system, phase and component levels. The system level depicts all possible executable paths of PMS via the token transition between different EOOPN subnets, including the re-execution arrangement of failed mission tasks. The phase level details the model structure of each EOOPN subnet, which addresses the system state change process and the minimal operational time requirement of a phase. The component level describes components state change during the mission. A discrete-event simulation is applied to the constructed EOOPNs for system mission reliability evaluation, and an example system under different time redundancy assumptions is analyzed to illustrate the effectiveness of this approach.