基于Petri网的导航卫星星座备份策略分析评估方法

针对北斗三号系统中轨道Walker导航星座的备份策略问题,提出基于随机时间Petri网(stochastic timed Petri net, STPN)的分析评估方法。通过构建单星、轨道面和导航星座的3层STPN模型,分析不同备份策略下星座运行的逻辑行为特性和操作事件的时序关系。建立导航星座的可用性模型和运行成本模型,作为导航星座备份策略的评估指标。最后,利用蒙特卡罗方法对所提出的分析模型的准确性进行评估,并在满足可用性的前提下以成本最小为标准，获得星座在不同条件下的最优备份策略。结果表明,该方法能有效分析不同备份策略对星座运行参数的影响,可为导航星座备份策略设计优化提供量化依据。

Analysis and evaluation method of navigation satellite constellation backup strategy based on Petri net

Aiming at the backup strategy of the medium orbit earth Walker navigation constellation of BDS-3,an analysis and evaluation method based on stochastic time Petri net(STPN)is proposed.By building a three layers STPN model of satellite,orbital plane and navigation constellation,the logical behavior characteristics of constellation operation and the timing relationship of operation event under different backup strategies are analyzed.The availability model and operation cost model of the navigation constellation are established as the evaluation index of the backup strategy of the navigation constellation.Finally,the Monte Carlo method is used to evaluate the accuracy of the proposed analysis model,and the optimal backup strategy of the constellation under different conditions is obtained based on the minimum cost under the availability.The results show that the method can effectively analyze the influence of the different backup strategies on constellation operation parameters,and provide quantitative bais for the design and optimization of the navigation constellation backup strategy.