Modeling And Simulation Of System Of Systems Based On Petri Nets

Recently, there has been a growing interests in a class of complex systems whose constituents are themselves complex and independent. These kind of systems is also called "System of Sytems"(SoS). Designing an SoS is a challenging work for its large-scales and complex interactivity. It is very necessary to design an efficient and correct model before the implementation because the real SoS can be extremely expensive and very hard to be tested. In this paper we are going to come up with a method for designing an effective and reliable model. Then we can improve the model by running simulations on this model and analyzing it.According to our method, to model an SoS, we need three steps:● Step 1:We use SysML to build a static model. SysML has a very strong ability to describe a complicated system. We can use the Requirement Diagram to analyze the requirement. We can use the Block Definition Diagram to decompose the SoS into several main parts. And we can use Activity Diagram/Sequence Diagram to describe the inner structure of the modules of the sub-systems.● Step 2:We then transform the static model into an executable model. Here we extended the UML/SysML Activity Diagram to record the time properties. Then the extended activity diagram can be transformed into Timed Coloured Petri Nets (TCPN). To give a formal transformation, we defined an Extended Activity Hy-perGraph (EAH), and mapped it into a Clocked Transition System (CTS). Thus, we assign the EAH model weak semantics. The EAH model is then become the intermediate model between activity diagram and TCPN model. The transforma-tion rules from activity diagrams to EAH model and from EAH model to TCPN model have been given separately.● Step 3:In the end, we discuss how to use CPN Tools to run simulations on the given TCPN models. Using CPN Tools, we can add data collectors to a specific transition node and count the data objects run through it. By analyzing the results, we can evaluate the system models.Two example systems were used in this thesis to discuss the modeling method. One is the Global Earth Observation System of Systems (GEOSS). This system is used for showing how to use SysML to get a static model of systems. The other system is a GameCapture Application which has some interactions with other applications and is performance critical. This application is used for showing the process of transformation from activity diagrams to the EAH models and from EAH models to TCPN models. And it also shows how to evaluate the systems by running the simulation on it.In this thesis, we put forward a method for modeling System of Systems on the base of previous works. We use the SysML for its strong ability to describe complicated systems. We use TCPN models because it is executable and analyzable. And we also give a formal transformation from activity diagram to TCPN Models.