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UBC Theses and Dissertations

Fault tolerant reconfiguration of multi-satellite interactions using high-level petri nets Einafshar, Atefeh


An integrated reconfiguration performance model for interacting satellite networks is an important tool in analyzing reliability and developing protocols for uninterrupted operation. However, such a quantitative model is not easy to develop since it involves many parameters related to the network’s operation and all the earth-linked operational information communicated through it. The aim of this study is to propose an integrated communication model for a network of interacting satellites using high-level petri nets which permit sub-network reconfiguration without loss of communication ability whenever there are satellite communication faults or full failures. To quantify the Vulnerability, Uncertainty and Probability (VUP) in a network a Stochastic Petri Net (SPN) based model is developed. Three indicators are proposed to determine the VUP definitions in interacting network of satellites. To model the overall reconfiguration schemes of a network of interacting satellites, Colored Petri Nets (CPN) paradigm is used so as to simulate the reconfiguration operation of the integrated Networked Control System (NCS). A modular representation of the interacting satellites with the network in terms of satellites’ subsystems and their interconnection together and through the network is provided. Transmission network is modeled through senders and receivers including packet-data transmission. The four developed reconfiguration methods are used to recover the network in case of partial/ full failures occur in the system. The proposed approaches are then used to study the overall response time of a given NCS in interacting satellites, as well as the delays between the mutual senders and receivers. Simulations of the detailed models show that the networked control performance of the interacting satellites, in particular with reference to any satellite failure, can be improved with inclusion of appropriate monitors within the networked system as represented by sub-networks in the CPN model. The suggested integrated networked control schemes can be used to obtain a fault tolerant reconfiguration for a required network performance.

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