Mixed-Criticality on the AFDX Network: Challenges and Potential Solutions

In this paper, we first assess the most relevant existing solutions enabling mixed-criticality on the AFDX and select the most adequate one. Afterwards, the specification of an extended AFDX, based on the Burst-Limiting Shaper (BLS), is detailed to fulfill the main avionics requirements and challenges. Finally, the preliminary evaluation of such a proposal is conducted through simulations. Results show its ability to guarantee the highest criticality traffic constraints, while limiting its impact on the current AFDX traffic

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

Runtime Monitoring On Hard Real-Time Operating Systems

This thesis will compare and evaluate different approaches in integrating runtime monitors into processes running on a hard real-time operating system. The host system is a single board computer (SBC) with a VxWorks 653 hard real-time operating system henceforth referred to as a flight control computer (FCC). The FCC is an integrated modular avionics (IMA) system representative of actual flight computers. VxWorks 653 is based on the ARINC 653 standard and provides time and space partitioning for IMA systems.M.S