Considerations about Continuous Experimentation for Resource-Constrained Platforms in Self-Driving Vehicles

Autonomous vehicles are slowly becoming reality thanks to the efforts of many academic and industrial organizations. Due to the complexity of the software powering these systems and the dynamicity of the development processes, an architectural solution capable of supporting long-term evolution and maintenance is required. Continuous Experimentation (CE) is an already increasingly adopted practice in software-intensive web-based software systems to steadily improve them over time. CE allows organizations to steer the development efforts by basing decisions on data collected about the system in its field of application. Despite the advantages of Continuous Experimentation, this practice is only rarely adopted in cyber-physical systems and in the automotive domain. Reasons for this include the strict safety constraints and the computational capabilities needed from the target systems. In this work, a concept for using Continuous Experimentation for resource-constrained platforms like a self-driving vehicle is outlined.Comment: Copyright 2017 Springer. Paper submitted and accepted at the 11th European Conference on Software Architecture. 8 pages, 1 figure. Published in Lecture Notes in Computer Science vol 10475 (Springer), https://link.springer.com/chapter/10.1007/978-3-319-65831-5_

Fault Confinement Mechanisms of the CAN Protocol : Analysis and Improvements

CAN (Controller Area Network) is a broadcast bus with priority based access to the medium which has become a de-facto standard for data transmissio- n in automotive applications. To prevent a defective node from perturbing the functioning of the whole system, for instance by repetitively sending error frames, the CAN protocol includes fault confinement mechanisms whose objectives are to detect permanent hardware dysfunctioning and to switch off defective nodes. In this study, we derive a Markovian analysis of these mechanisms and identify several shortages. New mechanisms that address theses problems are then proposed and we provide the algorithms for their implementation

Dynamic voltage scaling under EDF revisited

The original publication is available at www.springerlink.comInternational audienceBasic algorithms have been proposed in the field of low-power (Yao, F., et al. in Proceedings of lEEE annual foundations of computer science, pp. 374–382, 1995) which compute the minimum energy-schedule for a set of non-recurrent tasks (or jobs) scheduled under EDF on a dynamically variable voltage processor. In this study, we propose improvements upon existing algorithms with lower average and worst-case complexities. They are based on a new EDF feasibility test that helps to identify the “critical intervals”. The complexity of this feasibility test depends on structural characteristics of the set of jobs. More precisely, it depends on how tasks are included one in the other. The first step of the algorithm is to construct the Hasse diagram of the set of tasks where the partial order is defined by the inclusion relation on the tasks. Then, the algorithm constructs the shortest path in a geometrical representation at each level of the Hasse diagram. The optimal processor speed is chosen according to the maximal slope of each path

Maximizing the Robustness of TDMA Networks with Applications to TTP/C

In this study we show how one can use Fault-Tolerant Units (FTU) in an optimal way to make a TDMA network robust to bursty random perturbations. We consider two possible objectives. If one wants to minimize the probability of losing all replicas of a given message, then the optimal policy is to spread the replicas over time. This is proved using convexity properties of the loss probability. On the contrary if one wants to minimize the probability of losing at least one replica, then the optimal solution is to group all replicas together. This is proved by using majorization techniques. Finally we show how these ideas can be adapted for the TTP/C protocol

A New EDF Feasibility Test

We present a new algorithm for testing the feasibility of a set of non-recurrent tasks (or jobs) with real-time constraints scheduled under the EDF policy (Earliest Deadline First). The proposed feasibility test has a lower complexity than the previously known test. The first step of the algorithm is to construct the Hasse diagram of the set of tasks where the partial order is defined by the inclusion relation on the tasks. Then, the algorithm constructs the shortest path in a geometrical representation at each level of the Hasse diagram. Depending on the maximal slope of each path, the set of tasks is either feasible of not. The worst-case complexity of this feasibility test depends on structural characteristics of the set of jobs since it is the sum of the levels in the Hasse diagram. Whatever the set of jobs, this is better than the worst-case complexities of existing approaches. Furthermore, we provide a probabilistic analysis of the complexity when the tasks are random. For Poisson arrivals and exponentially distributed latencies, we show that the asymptotic complexity for assessing feasibility is O(N (N)). As an interesting by-product, the algorithm provides a new way to derive the best speeds of the processor so as to minimize the total energy consumption while meeting the deadline of each task. The exact complexity of this algorithm (sub-cubic in the number of tasks) is lower than the complexity of all the algorithms solving the same problem, known by the authors

Heterogeneous models and analyses in the design of real-time embedded systems - an avionic case-study

The development of embedded systems according to Model-Driven Development relies on two complementary activities: system mod- eling on the one hand and analysis of the non-functional properties, such as timing properties, on the other hand. Yet, the coupling be- tween 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 di erent levels of abstraction: the industry standard AADL (Ar- chitecture Analysis and Design Language) and the more recent implementation-oriented CPAL language (Cyber-Physical Action Language). We then combine di erent real-time scheduling analy- ses so as to gradually de ne the task and network parameters and nally validate the schedulability of all activities of the system

Ordonnancement temps réel et minimisation de la consommation d'énergie

La consommation en énergie est devenue un problème crucial dans la conception des équipements électroniques dont l'alimentation est assurée par des batteries. Parmi tous les composants électroniques, le processeur est particulièrement utilisateurs d'énergie puisque des études ([POU 01, ZEN 02] cités dans [AYD 04]) ont montré qu'il pouvait à lui seul utiliser plus de 50 % de l'énergie lorsqu'il était sollicité intensivement. En jouant sur une réduction de la fréquence de fonctionnement du processeur, des stratégies d'ordonnancement adaptées permettent de réduire considérablement la consommation énergétique. Nous proposons dans ce chapitre un tour d'horizon, dans le cas mono-processeur, des techniques d'ordonnancement visant à minimiser la consommation d'énergie tout en garantissant le respect de contraintes d'échéances. Les contraintes de temps peuvent peser explicitement sur certaines activités du système ou peuvent provenir de contraintes de performances minimales si l'on sort du cadre classique des systèmes temps réel. Le problème d'ordonnancement à résoudre consiste non seulement à déterminer l'ordre dans lequel exécuter les activités du système mais également à fixer la fréquence de fonctionnement du processeur au cours du temps. Comme souligné dans [GRU 02], l'ordonnancement sous contrainte d'énergie acquiert une nouvelle dimension qui est la vitesse du processeur

Establishment of a simple and efficient Agrobacterium-mediated transformation system for Phytophthora palmivora

BACKGROUND: As an agriculturally important oomycete genus, Phytophthora contains a large number of destructive plant pathogens that severely threaten agricultural production and natural ecosystems. Among them is the broad host range pathogen P. palmivora, which infects many economically important plant species. An essential way to dissect their pathogenesis mechanisms is genetic modification of candidate genes, which requires effective transformation systems. Four methods were developed for transformation of Phytophthora spp., including PEG(polyethylene glycol)/CaCl(2) mediated protoplast transformation, electroporation of zoospores, microprojectile bombardment and Agrobacterium-mediated transformation (AMT). Among them, AMT has many advantages over the other methods such as easy handling and mainly generating single-copy integration in the genome. An AMT method previously reported for P. infestans and P. palmivora has barely been used in oomycete research due to low success and low reproducibility. RESULTS: In this study, we report a simple and efficient AMT system for P. palmivora. Using this system, we were able to reproducibly generate over 40 transformants using zoospores collected from culture grown in a single 100 mm-diameter petri dish. The generated GFP transformants constitutively expressed GFP readily detectable using a fluorescence microscope. All of the transformants tested using Southern blot analysis contained a single-copy T-DNA insertion. CONCLUSIONS: This system is highly effective and reproducible for transformation of P. palmivora and expected to be adaptable for transformation of additional Phytophthora spp. and other oomycetes. Its establishment will greatly accelerate their functional genomic studies

Pushing the limits of CAN - scheduling frames with offsets provides a major performance boost

International audienceWith the increasing amount of electronics, making best usage of the bandwidth becomes of primary importance in automotive networks. One solution that is being investigated by car manufacturers is to schedule the messages with offsets, which leads to a desynchronization of the message streams. As it will be shown, this “traffic shaping” strategy is very beneficial in terms of worst-case response times. In this chapter, the problem of choosing the best offsets is addressed in the case of Controller Area Network, which is a de-facto standard in the automotive world. Comprehensive experiments shown in this chapter give insight into the fundamental reasons why offsets are efficient, and demonstrate that offsets actually provide a major performance boost in terms of response times. These experimental results suggest that sound off-set strategies may extend the lifespan of CAN further, and may defer the introduction of FlexRay and additional CAN networks