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See detailA Hybrid Machine Learning and Schedulability Method for the Verification of TSN Networks
Mai, Tieu Long UL; Navet, Nicolas UL; Migge, Jörn

Report (2019)

Machine learning (ML), and supervised learning in particular, can be used to learn what makes it hard for a network to be feasible and try to predict whether a network configuration will be feasible ... [more ▼]

Machine learning (ML), and supervised learning in particular, can be used to learn what makes it hard for a network to be feasible and try to predict whether a network configuration will be feasible without executing a conventional schedulability analysis. A disadvantage of ML-based timing verification with respect to schedulability analysis is the possibility of "false positives": configurations deemed feasible while they are not. In this work, in order to minimize the rate of false positives, we propose the use of a measure of the uncertainty of the prediction to drop it when the uncertainty is too high, and rely instead on schedulability analysis. In this hybrid verification strategy, the clear-cut decisions are taken by ML, while the more difficult ones are taken by a conventional schedulability analysis. Importantly, the trade-off achieved between prediction accuracy and computing time can be controlled. We apply this hybrid verification method to Ethernet TSN networks and obtain, for instance in the case of priority scheduling with 8 traffic classes, a 99% prediction accuracy with a speedup factor of 5.7 with respect to conventional schedulability analysis and a reduction of 46% of the false positives compared to ML alone. [less ▲]

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See detailUsing Machine Learning to Speed Up the Design Space Exploration of Ethernet TSN networks
Navet, Nicolas UL; Mai, Tieu Long UL; Migge, Jörn

Report (2019)

In this work, we ask if Machine Learning (ML) can provide a viable alternative to conventional schedulability analysis to determine whether a real-time Ethernet network meets a set of timing constraints ... [more ▼]

In this work, we ask if Machine Learning (ML) can provide a viable alternative to conventional schedulability analysis to determine whether a real-time Ethernet network meets a set of timing constraints. Otherwise said, can an algorithm learn what makes it difficult for a system to be feasible and predict whether a configuration will be feasible without executing a schedulability analysis? In this study, we apply standard supervised and unsupervised ML techniques and compare them, in terms of their accuracy and running times, with precise and approximate schedulability analyses in Network-Calculus. We show that ML techniques are efficient at predicting the feasibility of realistic TSN networks and offer new trade-offs between accuracy and computation time especially interesting for design-space exploration algorithms. [less ▲]

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See detailInsights into the performance and configuration of TCP in Automotive Ethernet Networks
Navet, Nicolas UL; Migge, Jörn

Scientific Conference (2018, October 10)

TCP has become an integral part of the Autosar communication stack located immediately below the Socket Adaptor layer. There are numerous use-cases for TCP in automotive networks. First TCP can be ... [more ▼]

TCP has become an integral part of the Autosar communication stack located immediately below the Socket Adaptor layer. There are numerous use-cases for TCP in automotive networks. First TCP can be leveraged on by many higher-level protocols be it for diagnostic (DoIp), calibration protocols (XCP), service-oriented communications (SomeIP), FTP and HTTP transfer, or more specialized tasks like protocols for the control of electric vehicle charging. In addition, communication through standard TCP sockets simplifies the development and re-use of applications requiring reliable transmissions within the vehicle or with external end-systems (car2x, cloud-based services).If previous works focused on throughput as performance criterion, we here also consider the communication latencies and memory usage in the end-systems and switches. The first question explored by simulation is to quantify the importance of TCP configuration choices in the latencies that can be achieved with TCP. In particular, it is shown that turning off Nagle's algorithm in transmission and delayed acknowledgment in reception as Autosar is very beneficial in terms of latencies but at the expense of throughput. We then extend the experiments to integrate the interactions between the Socket Adaptor and TCP layers. Finally, we study the performance of TCP streams as part of a complete automotive TSN case-study made up of control traffic, audio/video streams and best-effort traffic to evaluate the impact of higher priority traffic classes on TCP streams throughput and delays. The contribution of this work is twofold. First, we draw up a panorama of the TCP features and configuration options available in Autosar. Second, through experiments on models increasingly close to an implementation, we provide quantified insights in what we can expect from TCP in terms of latencies and throughput with the different configuration options available to us. [less ▲]

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See detailA journey into time-triggered communication protocols with a focus on Ethernet TSN
Navet, Nicolas UL

Presentation (2018, June 11)

This presentation provides an historical perspective on time-triggered (TT) protocols and highlights a few possible misconceptions about TT communication. The presentation is organized as follows: 1 ... [more ▼]

This presentation provides an historical perspective on time-triggered (TT) protocols and highlights a few possible misconceptions about TT communication. The presentation is organized as follows: 1) landscape of real-time (wired) communication networks, 2) Time-triggered (TT) protocols evolution: TTP, FlexRay, TTEthernet, TSN/TAS (IEEE802.1Qbv) 3) Misconceptions about TT communication 4) Takeaways and what is ahead of us. [less ▲]

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See detailTowards the Systematic Analysis of Non-Functional Properties in Model-Based Engineering for Real-Time Embedded Systems
Brau, Guillaume UL; Navet, Nicolas UL; Hugues, Jérôme

in Science of Computer Programming (2018), 156

The real-time scheduling theory provides analytical methods to assess the temporal predictability of embedded systems. Nevertheless, their use is limited in a Model-Based Systems Engineering approach. In ... [more ▼]

The real-time scheduling theory provides analytical methods to assess the temporal predictability of embedded systems. Nevertheless, their use is limited in a Model-Based Systems Engineering approach. In fact, the large number of applicability conditions makes the use of real-time scheduling analysis tedious and error-prone. Key issues are left to the engineers: when to apply a real-time scheduling analysis? What to do with the analysis results?} This article presents an approach to systematize and then automate the analysis of non-functional properties in Model-Based Systems Engineering. First, preconditions and postconditions define the applicability of an analysis. In addition, contracts specify the analysis interfaces, thereby enabling to reason about the analysis process. We present a proof-of-concept implementation of our approach using a combination of constraint languages (REAL for run-time analysis) and specification languages (Alloy for describing interfaces and reasoning about them). This approach is experimented on architectural models written with the Architecture Analysis and Design Language (AADL). [less ▲]

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See detailPre-shaping Bursty Transmissions under IEEE802.1Q as a Simple and Efficient QoS Mechanism
Navet, Nicolas UL; Migge, Jörn; Villanueva, Josetxo et al

in Proc. WCX World Congress Experience (2018, April)

The automotive industry is swiftly moving towards Ethernet as the high-speed communication network for in-vehicle communication. There is nonetheless a need for protocols that go beyond what standard ... [more ▼]

The automotive industry is swiftly moving towards Ethernet as the high-speed communication network for in-vehicle communication. There is nonetheless a need for protocols that go beyond what standard Ethernet has to offer in order to provide additional QoS to demanding applications such as ADAS systems or audio/video streaming. The main protocols currently considered for that purpose are IEEE802.1Q, AVB with the Credit Based Shaper mechanism (IEEE802.1Qav) and TSN with its Time-Aware Shaper (IEEE802.1Qbv). AVB/CBS and TSN/TAS both provide efficient QoS mechanisms and they can be used in a combined manner, which offers many possibilities to the designer. Their use however requires dedicated hardware and software components, and clock synchronization in the case of TAS. Previous studies have also shown that the efficiency of these protocols depends much on the application at hand and the value of the configuration parameters. In this work, we explore the use of “pre-shaping” strategies under IEEE802.1Q for bursty traffic such as audio/video streams as a simple and efficient alternative to AVB/CBS and TSN/TAS. Pre-shaping means inserting on the sender side “well-chosen” pauses between successive frames of a transmission burst (e.g., as it happens when sending a camera frame), all the other characteristics of the traffic remaining unchanged. We show on an automotive case-study how the use of pre-shaping for audio/video streams leads to a drastic reduction of the communication latencies for the best-effort streams while enabling to meet the timing constraints for the rest of the traffic. We then discuss the limitations of the pre-shaping mechanism and future works needed to facilitate its adoption. [less ▲]

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See detailA Model-Driven Co-Design Framework for Fusing Control and Scheduling Viewpoints
Sundharam, Sakthivel Manikandan UL; Navet, Nicolas UL; Altmeyer, Sebastian et al

in Sensors (2018), 18(2), 628

Model-Driven Engineering (MDE) is widely applied in the industry to develop new software functions and integrate them into the existing run-time environment of a Cyber-Physical System (CPS). The design of ... [more ▼]

Model-Driven Engineering (MDE) is widely applied in the industry to develop new software functions and integrate them into the existing run-time environment of a Cyber-Physical System (CPS). The design of a software component involves designers from various viewpoints such as control theory, software engineering, safety, etc. In practice, while a designer from one discipline focuses on the core aspects of his field (for instance, a control engineer concentrates on designing a stable controller), he neglects or considers less importantly the other engineering aspects (for instance, real-time software engineering or energy efficiency). This may cause some of the functional and non-functional requirements not to be met satisfactorily. In this work, we present a co-design framework based on timing tolerance contract to address such design gaps between control and real-time software engineering. The framework consists of three steps: controller design, verified by jitter margin analysis along with co-simulation, software design verified by a novel schedulability analysis, and the run-time verification by monitoring the execution of the models on target. This framework builds on CPAL (Cyber-Physical Action Language), an MDE design environment based on model-interpretation, which enforces a timing-realistic behavior in simulation through timing and scheduling annotations. The application of our framework is exemplified in the design of an automotive cruise control system. [less ▲]

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See detailInsights on the Performance and Configuration of AVB and TSN in Automotive Ethernet Networks
Migge, Jörn; Villanueva, Josetxo; Navet, Nicolas UL et al

in Proc. Embedded Real-Time Software and Systems (ERTS 2018) (2018, February 02)

Switched Ethernet is profoundly reshaping in-car communications. To meet the diverse real-time requirements in automotive communications, Quality-of-Service protocols that go beyond the mere use of ... [more ▼]

Switched Ethernet is profoundly reshaping in-car communications. To meet the diverse real-time requirements in automotive communications, Quality-of-Service protocols that go beyond the mere use of priorities are required. In this work, the basic questions that we investigate on a case-study with diverse and demanding communication requirements is what can we expect from the various protocols aimed at providing a better timing Quality of Service on top of Ethernet? And how to use them? Especially how to use them in a combined manner. We will focus on the Credit-Based Shaper of AVB, the Time-Aware Shaper of TSN and the use of priorities as defined in IEEE802.1Q. The performance metrics considered are the distributions of the communication latencies, obtained by simulation, as well as upper bounds on these quantities obtained by worst-case schedulability analysis. If there have been over the last 5 years numerous studies on the performance of AVB CBS, the literature on comparing AVB to TSN and other candidate protocols is still sparse. To the best of our knowledge, this empirical study is the first to consider most protocols currently considered in the automotive domain, with the aim to gain insights into the different technological, design and configurations alternatives. In particular, an objective of this study is to identify key problems that need to be solved in order to further automate network design and configuration. [less ▲]

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See detailSimulation-Based Fault Injection as a Verification Oracle for the Engineering of Time-Triggered Ethernet networks
Fejoz, Loïc; Regnier, Bruno; Miramont, Philippe et al

in Proc. Embedded Real-Time Software and Systems (ERTS 2018) (2018, February 02)

TTEthernet (TTE) is considered for use as high-speed backbone in the avionics of next-generation orbital space launchers. Given the key role of communication in launchers, the OEM must acquire a precise ... [more ▼]

TTEthernet (TTE) is considered for use as high-speed backbone in the avionics of next-generation orbital space launchers. Given the key role of communication in launchers, the OEM must acquire a precise understanding of TTE’s functioning and its performances in nominal and error conditions. This holds especially true for the clock synchronization algorithm, the cornerstone of time-triggered communication in TTE, which involves complex distributed algorithms. In this study, we use both an experimental platform and fault-injection on a simulation model to gain quantified insights in these questions. We first describe a fine-grained simulation model of TTE model and discuss how it has been validated against communication traces recorded on the TTE platform. We then present experiments that evaluate the accuracy of the clock synchronization in TTE in the fault-free case as well as considering permanent link failure and transient transmission errors. Finally, we discuss what we have learned during the project in terms of development process and programming language support for complex simulation models used in the design of critical systems. [less ▲]

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See detailPre-shaping Bursty Transmissions under IEEE802.1Q as a Simple and Efficient QoS Mechanism
Navet, Nicolas UL; Migge, Jörn; Villanueva, Josetxo et al

in SAE International Journal of Passenger Cars—Electronic and Electrical Systems (2018), 11(3),

The automotive industry is swiftly moving towards Ethernet as the high-speed communication network for in-vehicle communication. There is nonetheless a need for protocols that go beyond what standard ... [more ▼]

The automotive industry is swiftly moving towards Ethernet as the high-speed communication network for in-vehicle communication. There is nonetheless a need for protocols that go beyond what standard Ethernet has to offer in order to provide additional QoS to demanding applications such as ADAS systems (Advanced Driver-Assistance Systems) or audio/video streaming. The main protocols currently considered for that purpose are IEEE802.1Q, AVB with the Credit Based Shaper mechanism (IEEE802.1Qav) and TSN with its Time-Aware Shaper (IEEE802.1Qbv). AVB/CBS and TSN/TAS both provide efficient QoS mechanisms and they can be used in a combined manner, which offers many possibilities to the designer. Their use however requires dedicated hardware and software components, and clock synchronization in the case of TAS. Previous studies have also shown that the efficiency of these protocols depends much on the application at hand and the value of the configuration parameters. In this work, we explore the use of “pre-shaping” strategies under IEEE802.1Q for bursty traffic such as audio/video streams as a simple and efficient alternative to AVB/CBS and TSN/TAS. Pre-shaping means inserting on the sender side “well-chosen” pauses between successive frames of a transmission burst (e.g., as it happens when sending a camera frame), all the other characteristics of the traffic remaining unchanged. We show on an automotive case-study how the use of pre-shaping for audio/video streams leads to a drastic reduction of the communication latencies for the best-effort streams while enabling meeting the timing constraints for the rest of the traffic. We then discuss the limitations of the pre-shaping mechanism and what is needed to facilitate its adoption. [less ▲]

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See detailInsights on the performance and configuration of AVB and TSN in automotive applications
Navet, Nicolas UL; Villanueva, Josetxo; Migge, Jörn et al

Scientific Conference (2017, November 01)

Switched Ethernet is profoundly reshaping in-car communications. To meet the diverse real-time requirements in automotive communications, Quality-of-Service protocols that go beyond the mere use of ... [more ▼]

Switched Ethernet is profoundly reshaping in-car communications. To meet the diverse real-time requirements in automotive communications, Quality-of-Service protocols that go beyond the mere use of priorities are required. In this work, the basic questions that we investigate on a case-study with diverse and demanding communication requirements is what can we expect from the various protocols aimed at providing a better timing Quality of Service on top of Ethernet? And how to use them? Especially how to use them in a combined manner. We will focus on the Credit-Based Shaper of AVB, the Time-Aware Shaper of TSN and the use of priorities as defined in IEEE802.1Q. The performance metrics considered are the distributions of the communication latencies, obtained by simulation, as well as upper bounds on these quantities obtained by worst-case schedulability analysis. If there have been over the last 5 years numerous studies on the performance of AVB CBS, the literature on comparing AVB to TSN and other candidate protocols is still sparse. To the best of our knowledge, this empirical study is the first to consider most protocols currently considered in the automotive domain, with the aim to gain insights into the different technological, design and configurations alternatives. In particular, an objective of this study is to identify key problems that need to be solved in order to further automate network design and configuration. [less ▲]

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See detailHeterogeneous models and analyses in the design of real-time embedded systems - an avionic case-study
Brau, Guillaume UL; Navet, Nicolas UL; Hugues, Jérôme

in 25th International Conference on Real-Time Networks and Systems, Grenoble 4-6 October 2017 (2017, October)

The development of embedded systems according to Model-Driven Development relies on two complementary activities: system modeling on the one hand and analysis of the non-functional properties, such as ... [more ▼]

The development of embedded systems according to Model-Driven Development relies on two complementary activities: system modeling on the one hand and analysis of the non-functional properties, such as timing properties, on the other hand. Yet, the coupling between models and analyses remains largely disregarded so far: e.g., how to apply an analysis on a model? How to manage the analysis process? This paper presents an application of our research on this topic. In particular, we show that our approach makes it possible to combine heterogeneous models and analyses in the design of an avionic system. We use two languages to model the system at different levels of abstraction: the industry standard AADL (Architecture Analysis and Design Language) and the more recent implementation-oriented CPAL language (Cyber-Physical Action Language). We then combine different real-time scheduling analyses so as to gradually define the task and network parameters and finally validate the schedulability of all activities of the system. [less ▲]

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See detailModel-based design languages: A case study
Cibrario Bertolotti, Ivan; Hu, Tingting UL; Navet, Nicolas UL

in 2017 IEEE 13th International Workshop on Factory Communication Systems (WFCS) (2017)

Fast-paced innovation in the embedded systems domain puts an ever increasing pressure on effective software development methods, leading to the growing popularity of Model-Based Design (MBD). In this ... [more ▼]

Fast-paced innovation in the embedded systems domain puts an ever increasing pressure on effective software development methods, leading to the growing popularity of Model-Based Design (MBD). In this context, a proper choice of modeling languages and related tools - depending on design goals and problem qualities - is crucial to make the most of MBD benefits. In this paper, a comparison between two dissimilar approaches to modeling is carried out, with the goal of highlighting their relative advantages and shortcomings. It focuses on a case study involving a well-known distributed agreement protocol, a choice motivated by the fact that embedded systems are nowadays quickly evolving towards distributed, fault-tolerant architectures. [less ▲]

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See detailSoftware patterns for fault injection in CPS engineering
Navet, Nicolas UL; Cibrario Bertolotti, Ivan; Hu, Tingting UL

in 2017 22nd IEEE International Conference on Emerging Technologies and Factory Automation (ETFA) (2017)

Software fault injection is a powerful technique to evaluate the robustness of an application and guide in the choice of fault-tolerant mechanisms. It however requires a lot of time and know-how to be ... [more ▼]

Software fault injection is a powerful technique to evaluate the robustness of an application and guide in the choice of fault-tolerant mechanisms. It however requires a lot of time and know-how to be properly implemented, which severely hinders its applicability. We believe software fault injection can be made more “affordable” by automating it and have it integrated within a model-driven engineering design flow. We first propose in this paper a framework supporting these objectives. Then, illustrating on the domain-specific language CPAL, we present injection patterns that can be embedded in the application code and discuss the types of faults each supports, as well as implementation issues. [less ▲]

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See detailTowards Seamless Integration of N-Version Programming in Model-Based Design
Hu, Tingting UL; Cibrario Bertolotti, Ivan; Navet, Nicolas UL

in 22nd IEEE International Conference on Emerging Technologies And Factory Automation (ETFA’2017), Limassol, Cyprus, September 12-15 2017 (2017)

The ever-growing complexity of present-day software systems raises new and more stringent requirements on their availability, pushing designers to make use of sophisticated fault tolerance techniques far ... [more ▼]

The ever-growing complexity of present-day software systems raises new and more stringent requirements on their availability, pushing designers to make use of sophisticated fault tolerance techniques far beyond the areas they were traditionally conceived for, and bringing new challenges to both the modelling and implementation phases. In this paper, we propose a design pattern to model in a domain-specific language one of the prominent fault-tolerant techniques, namely the N-version programming. It can be integrated seamlessly into existing applications to enhance their functional correctness, while still preserving the timing characteristics, in particular the sampling times. Besides, it is also designed in a way to ease the automatic code generation. A counterpart of the same framework is also implemented in a lower-level programming language, for use when direct model execution is impractical, like in severely resource-limited embedded targets. [less ▲]

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See detailConnected Motorized Riders - A Smart Mobility System to Connect Two and Three-wheelers
Sundharam, Sakthivel Manikandan UL; Fejoz, Loic; Navet, Nicolas UL

in Proceedings of 6th Intentional Symposium on Embedded computing & system Design (ISED 2016) (2016, December 15)

The Smart Cities Mission has been launched in India in 2015 to develop 100 cities, with smart mobility being one of the main topics in the mission. As urban areas are flooded with two (motorcycles) and ... [more ▼]

The Smart Cities Mission has been launched in India in 2015 to develop 100 cities, with smart mobility being one of the main topics in the mission. As urban areas are flooded with two (motorcycles) and three wheelers (auto-rickshaws), introducing smart control of such vehicles may reduce the congestion on the roads and the number of accidents. Indeed, over-speeding and drunken driving are common traffic violations. In this project we propose an IoT-based smart mobility system which tracks data, such as the vehicle location, vehicle speed, alcohol level of the driver, etc. efficiently over the internet. Our system has been conceived with CPAL, a high-level language meant to simulate and execute Cyber Physical Systems including IoT applications. A prototype running on ARM mbed IoT hardware, shows the feasibility of our concept. We believe that more efficient and interactive traffic management, more disciplined driving behaviors, reduction in accident rate, more controlled pollution, increased passenger safety can be achieved if systems like the one prototyped in this work deployed contributing to smarter cities. [less ▲]

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See detailA Model-Based Development Environment for Rapid-Prototyping of Latency-Sensitive Automotive Control Software
Sundharam, Sakthivel Manikandan UL; Havet, Lionel; Altmeyer, Sebastian et al

in Proceedings of 6th Intentional Symposium on Embedded computing & system Design (ISED 2016) (2016, December 15)

The innovation in the field of automotive embedded systems has been increasingly relying on software-implemented functions. The control laws of these functions typically assume deterministic sampling ... [more ▼]

The innovation in the field of automotive embedded systems has been increasingly relying on software-implemented functions. The control laws of these functions typically assume deterministic sampling rates and constant delays from input to output. However, on the target processors, the execution times of the software will depend on many factors such as the amount of interferences from other tasks, resulting in varying delays from sensing to actuating. Three approaches supported by tools, namely TrueTime, T-Res, and SimEvents, have been developed to facilitate the evaluation of how timing latencies affect control performance. However, these approaches support the simulation of control algorithms, but not their actual implementation. In this paper, we present a model interpretation engine running in a co-simulation environment to study control performances while considering the run-time delays in to account. Introspection features natively available facilitate the implementation of self-adaptive and fault-tolerance strategies to mitigate and compensate the run-time latencies. A DC servo controller is used as a supporting example to illustrate our approach. Experiments on controller tasks with injected delays show that our approach is on par with the existing techniques with respect to simulation. We then discuss the main benefits of our development approach that are the support for rapid-prototyping and the re-use of the simulation model at run-time, resulting in productivity and quality gains. [less ▲]

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See detailRegime switching model for financial data: empirical risk analysis
Khaled, Salhi; Deaconu, Madalina; Lejay, Antoine et al

in Physica A: Statistical Mechanics and its Applications (2016), 461

This paper constructs a regime switching model for the univariate Value-at-Risk estimation. Extreme value theory (EVT) and hidden Markov models (HMM) are combined to estimate a hybrid model that takes ... [more ▼]

This paper constructs a regime switching model for the univariate Value-at-Risk estimation. Extreme value theory (EVT) and hidden Markov models (HMM) are combined to estimate a hybrid model that takes volatility clustering into account. In the first stage, HMM is used to classify data in crisis and steady periods, while in the second stage, EVT is applied to the previously classified data to rub out the delay between regime switching and their detection. This new model is applied to prices of numerous stocks exchanged on NYSE Euronext Paris over the period 2001–2011. We focus on daily returns for which calibration has to be done on a small dataset. The relative performance of the regime switching model is benchmarked against other well-known modeling techniques, such as stable, power laws and GARCH models. The empirical results show that the regime switching model increases predictive performance of financial forecasting according to the number of violations and tail-loss tests. This suggests that the regime switching model is a robust forecasting variant of power laws model while remaining practical to implement the VaR measurement. [less ▲]

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See detailModel Interpretation for an AUTOSAR compliant Engine Control Function
Sundharam, Sakthivel Manikandan UL; Altmeyer, Sebastian; Navet, Nicolas UL

in 7th International Workshop on Analysis Tools and Methodologies for Embedded and Real-time Systems (WATERS) (2016, July 05)

Model-Based Development (MBD) is a common practice in the automotive industry to develop complex software, for instance, the control software for automotive engines, which are deployed on modern multi ... [more ▼]

Model-Based Development (MBD) is a common practice in the automotive industry to develop complex software, for instance, the control software for automotive engines, which are deployed on modern multi-core hardware architectures. Such an engine control system consists of different sub-systems, ranging from air system to the exhaust system. Each of these subsystems, again, consists of software functions which are necessary to read from the sensors and write to the actuators. In this setting MBD provides indispensable means to model and implement the desired functionality, and to validate the functional, the non-functional, and in particular the real-time behavior against the requirements. Current industrial practice in model-based development completely relies on generative MBD, i.e., code generation to bridge the gap between model and implementation. An alternative approach, although not yet used in the automotive domain is model interpretation, the direct interpretation of the design models using interpretation engine running on top of the hardware. In this paper, we present a case study to investigate the applicability of model interpretation, in contrast to code generation, for the development of engine control systems. To this end, we model an engine cooling system, specifically the calculation of the engine-coolant temperature, using interpreted model based development, and discuss the benefits and low-lights compared to the existing code generation practice. [less ▲]

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See detailThe use of simulation in the design of critical embedded systems
Navet, Nicolas UL

Scientific Conference (2016, June 09)

Les plate-formes virtuelles permettant de prédire par simulation numérique les performances deviennent peu à peu une réalité dans la conception des systèmes de contrôle les plus complexes et les plus ... [more ▼]

Les plate-formes virtuelles permettant de prédire par simulation numérique les performances deviennent peu à peu une réalité dans la conception des systèmes de contrôle les plus complexes et les plus contraints (automobile, aéronautique, contrôle de réseaux power-grid, etc). Dès les phases amont du cycle de conception, ces outils guident les concepteurs dans leurs choix de conception. Le premier objectif de cet exposé est de dresser un rapide panorama des modèles et techniques de simulation de l'embarqué critique: simulation du comportement fonctionnel (lois de contrôle), simulation "timing-accurate" des plate-formes d'exécution, de leur complémentarité et limites actuelles. Contrairement à des techniques mathématiques, la simulation ne fournit a priori aucune garantie sur la couverture de vérification et les situations pire-cas ("corner cases") ne sont pas nécessairement identifiées. Néanmoins la simulation est de plus en plus incontournable car les modèles analytiques ne sont généralement pas en mesure de capturer toute la complexité des systèmes réels. Le second objectif de cet exposé est d'identifier des bonnes pratiques méthodologiques pour l'utilisation de la simulation dans les systèmes critiques (ex: choix des temps de simulation et nombre d'expérimentations en fonction de caractéristiques structurelles des processus simulés, métriques de performances pour les événements rares, etc). [less ▲]

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