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Dimensioning of Civilian Avionics Networks
Published in Richard Zurawski, Industrial Communication Technology Handbook, 2017
Jean-Luc Scharbarg, Christian Fraboul
The evolution of civilian aircraft avionics systems is mainly due to an increasing complexity, which is illustrated by a larger number of integrated functions, a larger volume of exchanged data, and a larger number of connections between functions. Consequently, the growth of the number of multipoint communication links cannot be taken into account by classical avionics mono-emitter data–buses (such as ARINC 429 [ARI01]). A first solution proposed for Boeing 777 led to the design of a new multiplexed data–bus based on CSMA-CA medium access control (ARINC 629 standard [ARI99]). The solution adopted by Airbus for the A380 consists in the utilization of a switched Ethernet technology (AFDX: Avionics Full Duplex Switched Ethernet), which allows a reuse of development tools as well as of existing communication components while achieving better performance and which has been standardized in ARINC 664 [ARI02,ARI03]. This new communication standard represents a major step in the deployment of modular avionics architectures (Integrated Modular Avionics: IMA ARINC 651 [ARI91] and 653 [ARI97]). But the main problem is due to the indeterminism of the switched Ethernet, and a network designer must prove that no frame will be lost by the AFDX (no switch queue overflow) and must evaluate the end-to-end transfer delay through the network (guaranteed upper bound and distribution of delays) according to a given avionics applications traffic.
Modelling and temporal evaluation of networked control systems using timed automata with guards and (max,+) algebra
Published in International Journal of Systems Science, 2018
Currently, the industrial processes are more and more automated, and human intervention is becoming rare. Initially, the control systems were centralised and a computer could control an entire production site. But, for reasons of dependability and economy of resources, the distributed control schemes, commonly called Networked Control Systems (NCS), have been privileged. These latter allow a very large data transfer thanks to the high bandwidth and reliable data exchange (check-sum, parity bits, etc.) between the different field components (controller, sensors, actuators, etc.) and prevent the unavailability of a part of the process or its entirety due to a single failure. On the other side, this has introduced new challenges that are mainly the interoperability and the performance. The first challenge is due to the large set of protocols and technologies that were developed by the different constructors. With regard to the second challenge, the limited quantity of the resources implies low performances that can range from delays to the data-packet losses due to the overflow of the resources in the worst case. The first challenge has been solved through the development of the industrial Ethernet which standardised protocols and technologies developed by many constructors. Likewise, the development of some Ethernet-based architectures for critical applications such as Avionics Full-Duplex Switched Ethernet and PowerLink Ethernet have solved the problem of packet collision. Finally, the reactivity of NCS subject to different real-time requirements must always be evaluated before its implementation. Depending on whether the expected performances meet the requirements or not, the implementation of the system can be confirmed, the requirements reviewed or the system components and capacity changed.