Ejemplos prácticos de aplicación de buses en aeronaves

El objetivo de este trabajo es estudiar la manera de crear una representación de una red aviónica, para poder modificarla y capturar resultados con el fin de analizar los comportamientos de la red, y crear ejemplos y ejercicios para su uso en el estudio de los protocolos de comunicación aeronáuticos. Los protocolos de comunicación escogidos para este proyecto son TTEthernet (Time-Triggered Ethernet) y AFDX (Avionics Full Duplex Switched Ethernet), dos protocolos basados en el estándar Ethernet IEEE 802.3, full duplex, deterministas, con topología de estrella y con altas tasas de transmisión que ayudan a reducir el peso del cableado comparado con otros estándares utilizados en la aviónica. Para la creación de la aplicación se ha utilizado el software informático OMNeT++, un simulador modular y extensible de redes basado en el lenguaje de programación C++, con representación gráfica de la red simulada a tiempo real, que permite pausar la simulación para comprobar el estado de los nodos, o el contenido de los mensajes. El trabajo se divide en dos partes, una primera que trata el primer protocolo TTEthernet, y la segunda parte trata AFDX. En cada parte se explica el funcionamiento del estándar pertinente, cuáles son sus características, y que estrategias usa para adaptar Ethernet al mundo aeronáutico. A continuación se explica su implementación en OMNeT++, las pruebas realizadas sobre esa red creada, análisis de los resultados recogidos por el sistema y posibles ejercicios relacionados la simulación. Seguido de estos dos capítulos hay unas conclusiones generales sobre el proyecto seguidas por un anexo. En el anexo se detalla información que ayuda a poner en contexto el trabajo, series de capturas de las simulaciones y código utilizado en para crear la simulación de la red aeronáutica de comunicaciones.The objective of this project is to study how to build an avionics communication system application, being able to modify it and capture the results in order to analyse the behaviour of the network, with the intention of create examples and tests for the academic purpose of studying aeronautic communication protocols. The protocols studied in this project are TTEthernet (Time-Triggered Ethernet) and AFDX (Avionics Full Duplex Switched Ethernet), both of them based in IEEE 802.3 Ethernet standard, being full duplex, deterministic, using star-topology, with high transmission rates and less weight with the use of less cable compared with older avionics communication standards. The application is build using OMNeT++ informatic software, an extensible and modular network simulator based on C++ programming language. This simulator features a graphic representation of the network simulated on real time, being able to pause the simulation and check messages content and devices status. The project is divided into two different parts, the first one contains the work related with TTEthernet and the second one with AFDX. Each part explains the basics of the protocol, like characteristics, modifications to Ethernet standard to make it compatible with aeronautics requirements, word structure, etc. Next is explained how is created a network using this protocol in OMNeT++, the test performed, the analysis of the gathered data and an approach to create practical exercises with the simulation. Following these two parts there are a general conclusion of the project. In the annex there is information useful to understand the background of the project, a series of captures of the simulation and code used to create the network studied

One solution for TTEthernet synchronization analysis using genetic algorithm

Bezbjednosno-kritični sistemi poput aviona ili automobila zahtijevaju visoko-pouzdanu razmjenu poruka između uređaja u sistemu, što se postiže primjenom determinističkih mreža. Pravilno uspostavljanje međusobne usklađenosti časovnika, kao i konstantno održavanje vremenske usklađenosti, svrstavaju se među najbitnije aspekte determinističkih mreža među kojima su i TTEthernet mreže. Ukoliko časovnici mrežnih uređaja nisu vremenski usklađeni, deterministička razmjena poruka u mreži nije izvodljiva. S obzirom da se informacije o najkritičnijim funkcijama sistema prenose preko determinističke klase poruka, očigledno je da ovakvi servisi neće biti dostupni sve dok se časovnici ne usklade. Teza se bavi procjenom najgoreg slučaja vremena koje je potrebno da protekne da bi se časovnici mrežnih uređaja međusobno uskladili, u slučaju da u mreži postoji jedan uređaj pod otkazom. Procjene su vršene pomoću OMNeT++ simulacija uz primjenu genetskog algoritma. Simulacije pokazuju da se vrijeme neophodno da se uspostavi usklađenost časovnika u TTEthernet mreži značajno povećava pod uticajem uređaja pod otkazom, a samim tim se produžava i vrijeme nedostupnosti najkritičnijih servisa mreže. Simulacije pokazuju da se za mrežu posmatranu u tezi, za izabrane parametre mreže dobija procijenjena vrijednost medijane jednaka 489579μs za najgori slučaj uspostavljanja vremenske usklađenosti u mreži.Safety-critical systems like airplanes and cars demand high-reliable communication between components within the system, which is achieved by using deterministic networks. Proper establishing and maintenance of synchronization of device clocks in the network components represents one of crucial aspects in deterministic networks where belong TTEthernet as well. If device clocks are not synchronized, deterministic communication is not feasible. Keeping in mind that most critical information has been exchanged between the network components using deterministic traffic class, it is obvious that such services will not be available until the clocks in the network are synchronized. The thesis deals with estimation of worst-case startup time for observed TTEthernet network, in case that one device in the network is under failure. The estimation is performed by OMNeT++ simulations and using genetic algorithm. The simulations show that startup time of the network is extended significantly under impact of faulty component. Also, unavailability of most critical services in the network is extended for the same time. For the network simulated in this thesis, estimated median value equals 489579 μs for worst-case startup time