144 research outputs found
NetGAP: A Graph-Grammar approach for concept design of networked platforms with extra-functional requirements
During the concept design of complex networked systems, concept developers
have to assure that the choice of hardware modules and the topology of the
target platform will provide adequate resources to support the needs of the
application. For example, future-generation aerospace systems need to consider
multiple requirements, with many trade-offs, foreseeing rapid technological
change and a long time span for realization and service. For that purpose, we
introduce NetGAP, an automated 3-phase approach to synthesize network
topologies and support the exploration and concept design of networked systems
with multiple requirements including dependability, security, and performance.
NetGAP represents the possible interconnections between hardware modules using
a graph grammar and uses a Monte Carlo Tree Search optimization to generate
candidate topologies from the grammar while aiming to satisfy the requirements.
We apply the proposed approach to the synthetic version of a realistic avionics
application use case and show the merits of the solution to support the
early-stage exploration of alternative candidate topologies. The method is
shown to vividly characterize the topology-related trade-offs between
requirements stemming from security, fault tolerance, timeliness, and the
"cost" of adding new modules or links. Finally, we discuss the flexibility of
using the approach when changes in the application and its requirements occur
Tехнічні засоби діагностування та контролю бортових систем інформаційного обміну на літаку
Робота публікується згідно наказу ректора від 27.05.2021 р. №311/од "Про розміщення кваліфікаційних робіт вищої освіти в репозиторії НАУ". Керівник дипломної роботи: доцент кафедри авіоніки, Слободян Олександр ПетровичТехнічний прогрес в авіаційній та будь-якій іншій галузі тісно пов'язаний з
автоматизацією технологічних процесів. Сьогодні Автоматизація
технологічних процесів використовується для підвищення характеристик
надійності, довговічності, екологічності, ресурсозбереження і, найголовніше,
економічності і простоти експлуатації. Завдяки швидкому розвитку
комп'ютерних технологій і мікропроцесорів у нас є можливість
використовувати більш досконалі і складні методи моніторингу та
управління системами авіаційної промисловості і будь-якими іншими.
Мікропроцесорні та електронні обчислювальні пристрої, з'єднані
обчислювальними і керуючими мережами з використанням загальних баз
даних, мають стандарти, що дозволяють модифікувати і інтегрувати нові
пристрої, що, в свою чергу, дозволяє інтегрувати і вдосконалювати
виробничі процеси і управляти ними.
Проектування системи розподіленої інтегрованої модульної авіоніки
(DIMA) з використанням розподіленої інтегрованої технології, змішаного
планування критичних завдань, резервний планування в режимі реального
часу і механізму зв'язку, який запускається за часом, значно підвищує
надійність, безпеку і продуктивність інтегрованої електронної системи в
режимі реального часу. DIMA являє собою тенденцію розвитку майбутніх
систем авіоніки. У цій статті вивчаються і обговорюються архітектурні
характеристики DIMA. Потім він детально вивчає та аналізує розвиток
ключових технологій в системі DIMA. Нарешті, в ньому розглядається
тенденція розвитку технології DIMA
Differentiable Programming & Network Calculus: Configuration Synthesis under Delay Constraints
With the advent of standards for deterministic network behavior, synthesizing
network designs under delay constraints becomes the natural next task to
tackle. Network Calculus (NC) has become a key method for validating industrial
networks, as it computes formally verified end-to-end delay bounds. However,
analyses from the NC framework have been designed to bound the delay of one
flow at a time. Attempts to use classical analyses to derive a network
configuration have shown that this approach is poorly suited to practical use
cases. Consider finding a delay-optimal routing configuration: one model had to
be created for each routing alternative, then each flow delay had to be
bounded, and then the bounds had to be compared to the given constraints. To
overcome this three-step process, we introduce Differential Network Calculus.
We extend NC to allow the differentiation of delay bounds w.r.t. to a wide
range of network parameters - such as flow paths or priority. This opens up NC
to a class of efficient nonlinear optimization techniques that exploit the
gradient of the delay bound. Our numerical evaluation on the routing and
priority assignment problem shows that our novel method can synthesize flow
paths and priorities in a matter of seconds, outperforming existing methods by
several orders of magnitude
Time-Sensitive Networking for Industrial Automation: Challenges, Opportunities, and Directions
With the introduction of Cyber-Physical Systems (CPS) and Internet of Things
(IoT) into industrial applications, industrial automation is undergoing
tremendous change, especially with regard to improving efficiency and reducing
the cost of products. Industrial automation applications are often required to
transmit time- and safety-critical data to monitor and control industrial
processes, especially for critical control systems. There are a number of
solutions to meet these requirements (e.g., priority-based real-time schedules
and closed-loop feedback control systems). However, due to their different
processing capabilities (e.g., in the end devices and network switches),
different vendors may come out with distinct solutions, and this makes the
large-scale integration of devices from different vendors difficult or
impossible. IEEE 802.1 Time-Sensitive Networking (TSN) is a standardization
group formed to enhance and optimize the IEEE 802.1 network standards,
especially for Ethernet-based networks. These solutions can be evolved and
adapted into a cross-industry scenario, such as a large-scale distributed
industrial plant, which requires multiple industrial entities working
collaboratively. This paper provides a comprehensive review on the current
advances in TSN standards for industrial automation. We present the
state-of-the-art IEEE TSN standards and discuss the opportunities and
challenges when integrating each protocol into the industry domains. Finally,
we discuss some promising research about applying the TSN technology to
industrial automation applications
A Real-time Calculus Approach for Integrating Sporadic Events in Time-triggered Systems
In time-triggered systems, where the schedule table is predefined and
statically configured at design time, sporadic event-triggered (ET) tasks can
only be handled within specially dedicated slots or when time-triggered (TT)
tasks finish their execution early. We introduce a new paradigm for
synthesizing TT schedules that guarantee the correct temporal behavior of TT
tasks and the schedulability of sporadic ET tasks with arbitrary deadlines. The
approach first expresses a constraint for the TT task schedule in the form of a
maximal affine envelope that guarantees that as long as the schedule generation
respects this envelope, all sporadic ET tasks meet their deadline. The second
step consists of modeling this envelope as a burst limiting constraint and
building the TT schedule via simulating a modified Least-Laxity-First (LLF)
scheduler. Using this novel technique, we show that we achieve equal or better
schedulability and a faster schedule generation for most use-cases compared to
other approaches inspired by, e.g., hierarchical scheduling. Moreover, we
present an extension to our method that finds the most favourable schedule for
TT tasks with respect to ET schedulability, thus increasing the probability of
the computed TT schedule remaining feasible when ET tasks are later added or
changed
Real-time analysis of MPI programs for NoC-based many-cores using time division multiplexing
Worst-case execution time (WCET) analysis is crucial for designing hard real-time systems. While the WCET of tasks in a single core system can be upper bounded in isolation, the tasks in a many-core system are subject to shared memory interferences which impose high overestimation of the WCET bounds. However, many-core-based massively parallel applications will enter the area of real-time systems in the years ahead. Explicit message-passing and a clear separation of computation and communication facilitates WCET analysis for those programs.
A standard programming model for message-based communication is the message passing interface (MPI). It provides an application independent interface for different standard communication operations (e.g. broadcast, gather, ...). Thereby, it uses efficient communication patterns with deterministic behaviour. In applying these known structures, we target to provide a WCET analysis for communication that is reusable for different applications if the communication is executed on the same underlying platform. Hence, the analysis must be performed once per hardware platform and can be reused afterwards with only adapting several parameters such as the number of nodes participating in that communication. Typically, the processing elements of many-core platforms are connected via a Network-on-Chip (NoC) and apply techniques such as time-division multiplexing (TDM) to provide guaranteed services for the network. Hence, the hardware and the applied technique for guaranteed service needs to facilitate this reusability of the analysis as well.
In this work we review different general-purpose TDM schedules that enable a WCET approximation independent of the placement of tasks on processing elements of a many-core which uses a NoC with torus topology. Furthermore, we provide two new schedules that show a similar performance as the state-of-the-art schedules but additionally serve situations where the presented state-of-the-art schedules perform poorly. Based on these schedules a procedure for the WCET analysis of the communication patterns used in MPI is proposed. Finally, we show how to apply the results of the analysis to calculate the WCET upper bound for a complete MPI program.
Detailed insights in the performance of the applied TDM schedules are provided by comparing the schedules to each other in terms of timing. Additionally, we discuss the exhibited timing of the general-purpose schedules compared to a state-of-the-art application specific TDM schedule to put in relation both types of schedules. We apply the proposed procedure to several standard types of communication provided in MPI and compare different patterns that are used to implement a specific communication. Our evaluation investigates the communications’ building blocks of the timing bounds and shows the tremendous impact of choosing the appropriate communication pattern. Finally, a case study demonstrates the application of the presented procedure to a complete MPI program.
With the method proposed in this work it is possible to perform a reusable WCET timing analysis for the communication in a NoC that is independent of the placement of tasks on the chip. Moreover, as the applied schedules are not optimized for a specific application but can be used for all applications in the same way, there are only marginal changes in the timing of the communication when the software is adapted or updated. Thus, there is no need to perform the timing analysis from scratch in such cases
CarRing IV- Real-time Computer Network
Ob in der Automobil-, Avionik- oder Automatisierungstechnik, die Fortschritte in der
Echtzeitkommunikation richten sich auf weitere Verbesserungen bereits existierender
Lösungen. Im Kfz-Bereich führen die steigenden Zahlen computerbasierter Systeme,
Anwendungen und Anschlüsse sowie die Verwendung mehrerer proprietärer Kommunikationsstandards zu einem immer komplexeren Kabelbaum. Ursächlich hierfür sind
inkompatible Standards, wodurch nicht nur die Kosten, sondern auch das Gewicht
und damit der Kraftstoffverbrauch negativ beeinflusst werden.
Im ersten Teil der Dissertation wird das Echtzeitprotokoll von CarRing IV (CRIV) vorgestellt. Es bietet isochrone und harte Echtzeitgarantien, ohne dass eine netzwerkweite Synchronisation erforderlich ist. Mit bis zu 16 Knoten pro Ring kann
ein CR-IV-Netz aus bis zu 256 Ringen bestehen, die durch Router miteinander verbunden sind. CR-IV verwendet ein reduziertes OSI-Modell (Schichten 1-3, 7), das
für seine Anwendungsbereiche sowohl typisch als auch vorteilhaft ist. Außerdem
unterstützt es sowohl ereignis- als auch zeitgesteuerte Kommunikationsparadigmen.
Der Transparent-Modus ermöglicht es CR-IV, als Backbone für bestehende Netze
zu verwenden, wodurch Inkompatibilitätsprobleme beseitigt werden und der Wechsel zu einer einheitlicheren Netzlösung erleichtert wird. Mit dieser Funktionalität
können Nutzergeräte über ein CR-IV-Netz miteinander verbunden werden, ohne dass
der Nutzer eingreifen oder etwas ändern muss. Durch Multicast unterstützt CRIV auch die Emulation von Feldbussen. Der zweite Teil der Dissertation stellt den
anderen wichtigen Aspekt von CR-IV vor. Alle Schichten des OSI-Modells sind in
einem FPGA mit Hardware Description Languages (HDLs) ohne Hard- oder Softprozessoren implementiert. Das Register-Transfer-Level (RTL)-Hardwaredesign von
CR-IV wird mit einem neuen Ansatz erstellt, der am besten als tokenbasierter Datenfluss beschrieben werden kann. Der Ansatz ist sowohl vertikal als auch horizontal
skalierbar. Er verwendet lose gekoppelte Processing Elements (PEs), die stateless arbeiten, sowie Arbiter/Speicherzuordnungspaare. Durch die granulare Kontrolle und
die Aufteilung aller Aspekte einer Lösung eignet sich der Ansatz für die Implementierung anderer Software-Level-Lösungen in Hardware.
Viele Testszenarios werden durchgeführt, um die in CR-IV erzielten Ergebnisse zu
verdeutlichen und zu überprüfen. Diese Szenarien reichen von direkten Leistungsmessungen bis hin zu verhaltensspezifischen Tests. Zusätzlich wird eine Labor-Demo
erstellt, die grundsätzlich auf ein Proof of Concept zielt. Die Demo stellt einen
praktischen Test anstelle szenariospezifischer Tests dar. Alle Testszenarien und die
Labor-Demo werden mit den Prototyp-Boards des Projekts durchgef¨uhrt, d.h. es sind
keine Simulationstests. Die Ergebnisse stellen die realistischen Leistungen von CR-IV
mit bis zu 13,61 Gbit/s dar.Whether be it automotive, avionics or automation, advances in their respective real-time communication technology focus on further improving preexisting solutions. For
in-vehicle communication, the ever-increasing number of computer-based systems,
applications and connections as well as the use of multiple proprietary communication
standards results in an increasingly complex wiring harness. This is in-part due to
those standards being incompatible with one another. In addition to cost, this also
impacts weight, which in turn affects fuel consumption.
The work presented in this thesis is in-part theoretical and in-part applied. The
former is represented by a new protocol, while the latter corresponds to the protocol’s
hardware implementation. In the first part of the thesis, the real-time communication protocol of CarRing IV (CR-IV) is presented. It provides isochronous and hard
real-time guarantees without requiring network-wide clock synchronization. With up
to 16 nodes per ring, a CR-IV network can consist of as many as 256 rings interconnected by routers. CR-IV uses a reduced OSI model (layers 1-3, 7), which is both
typical of and preferable for its application areas. Moreover, it supports both event- and time-triggered communication paradigms. The transparent mode feature allows
CR-IV to act as a backbone for existing networks, thereby addressing incompatibility
concerns and easing the transition into a more unified network solution. Using this
feature, user devices can communicate with one another via a CR-IV network without
requiring user interference, or any user device or application changes. Combined with
the protocol’s reliable multicast, the feature extends CR-IV’s capabilities to include
field bus emulation. The second part of the thesis presents the other important aspect
of CR-IV. All of its OSI model layers are implemented in a FPGA using Hardware
Description Languages (HDLs) without relying-on or including any hard or soft processors. CR-IV’s Register-Transfer Level (RTL) hardware design is created using a new
approach that can best be described as token-based data-flow. The approach is both
vertically and horizontally scalable. It uses stateless and loosely coupled Processing
Elements (PEs) as well as arbiter/memory allocation pairs. By having granular control and compartmentalizing every aspect of a solution, the approach lends itself to
being used for implementing other software-level solutions in hardware.
Many test scenarios are conducted to both highlight and examine the results
achieved in CR-IV. Those scenarios range from direct performance measurements to
behavior-specific tests. Moreover, a lab-demo is created that essentially amounts to
a proof of concept. The demo represents a practical test as opposed to a scenariospecific one. Whether be it test scenarios or the lab-demo, all are carried-out using the
project’s prototype boards, i.e. no simulation tests. The results obtained represent
CR-IV’s real-world realistic outcomes with up to 13.61 Gbps
Time Sensitive Networking Protocol Implementation for Linux End Equipment
By bringing industrial-grade robustness and reliability to Ethernet, Time Sensitive Networking (TSN) offers an IEEE standard communication technology that enables interoperability between standard-conformant industrial devices from any vendor. It also eliminates the need for physical separation of critical and non-critical communication networks, which allows a direct exchange of data between operation centers and companies, a concept at the heart of the Industrial Internet of Things (IIoT). This article describes creating an end-to-end TSN network using specialized PCI Express (PCIe) cards and two final Linux endpoints. For this purpose, the two primary standards of TSN, IEEE 802.1AS (regarding clock synchronization), and IEEE 802.1Qbv (regarding time scheduled traffic) have been implemented in Linux equipment as well as a configuration and monitoring system.This work has been supported by the Ministerio de Economía y Competitividad of Spain
within the project TEC2017-84011-R and FEDER funds as well as by the Department of Education
of the Basque Government within the fund for research groups of the Basque university system
IT978-16
Mixed Criticality Systems - A Review : (13th Edition, February 2022)
This review covers research on the topic of mixed criticality systems that has been published since Vestal’s 2007 paper. It covers the period up to end of 2021. The review is organised into the following topics: introduction and motivation, models, single processor analysis (including job-based, hard and soft tasks, fixed priority and EDF scheduling, shared resources and static and synchronous scheduling), multiprocessor analysis, related topics, realistic models, formal treatments, systems issues, industrial practice and research beyond mixed-criticality. A list of PhDs awarded for research relating to mixed-criticality systems is also included
- …