The tracking, telemetry and command （TT＆C） mission is extremely reliable for its characters of small time horizon and high redundancy. The combined forcing and failure biasing （CFFB） method that is usually used for simulating the unreliability of the highly dependable mission system seems not so efficient for the TT＆C mission. The concept about the importance of failure transition is proposed based on the logical relationship between TT＆C mission and its involved resources. Then, the importance is used for readjusting the transition rate of the failure transition when using the forcing and failure biasing during the simulation. Examples show that the improved CFFB method can evidently increase the occurrence of the TT＆C mission failure event and decrease the sample variance. More redundancy of the TT＆C mission leads to the improved CFFB method more efficient.
提出了一种可用于航天测控系统任务可靠性分析的扩展面向对象Petri网(Extend ObjectOriented Petri Nets,EOOPN)模型,旨在对给定的航天测控方案进行可靠性评估分析。针对问题特点明确了OOPN扩展思路,给出了EOOPN模型的形式化定义、运行规则和建模步骤,模型通过引入公共库所、激发弧、消息变迁和消息处理函数等概念,体现了面向对象的思想,具有很好的层次性和模块性。所建立的EOOPN模型能够完整地描述航天测控系统的组成和任务特点。通过对算例模型仿真运行,表明实验结果具有良好收敛性,与Markov解析值对比误差在1%以内,从而验证了模型的有效性。
针对复杂系统任务可靠性建模分析问题,提出了一种扩展的面向对象的Petri网(extended object oriented Petri net,EOOPN)模型。EOOPN模型具有层次化的结构,使用子网对组成复杂系统的各子系统进行建模,提高了模型的模块化程度;引入逻辑门变迁增加了变迁触发条件的直观性;使用广播库所降低了模型结构表示的复杂性。最后,通过一个反导系统示例验证了EOOPN模型在复杂系统任务可靠性建模分析中的应用。
A comprehensive mission sensitivity analysis index based on Sobol's index called global mission sensitivity( GMS) was proposed in this paper which focused on analyzing the mission sensitivity of components of phased mission systems( PMS). The simulation strategy of GMS based on a Petri net and Monte Carlo method was presented which had broad applicability. Finally,the GMS and Birnbaum's sensitivity of components in a PMS example were compared. The GMS of component is demonstrated to be more adaptable to reflect the component mission sensitivity when the rated reliability parameters of components cannot be obtained, and components have state dependency or the system is subjected to common cause failure.
