Evaluating Quality of Service and Behavioral Reliability of Steer-by-Wire Systems

Best Paper Award on Factory Automation. Colloque avec actes et comité de lecture. internationale.International audienceSteer-by-wire systems must meet not only reliability but also real-time requirements. This paper presents an integrated approach for evaluating both the temporal performance and the behavioral reliability of Steer-by-wire systems taking into account the delay variation introduced by network transmission errors. The considered temporal performance is the Quality of Service perceived by the user, i.e. the vehicle stability. Tests in vehicles and simulations have been realized to estimate the maximum tolerable response time of the system, and to evaluate the impact of this delay on the Quality of Service. We quantify then the worst case response time of the system for a generic architecture based on TDMA protocol but independent of the communication network (could actually be TTP/C or FlexRay), and apply these generic results to a case study. We further define the notion of behavioral reliability as the probability that the worst case response time is less than a threshold. In our case study this behavioral reliability is evaluated and linked to the Safety Integrity Levels defined in IEC61508-1 standard. Based on this behavioral reliability concept, the final objective of our work is to propose a new dependability analysis method for X-by-Wire systems by taking into account both dynamic performance, fault-tolerance mechanisms and static redundancy of the system . || Les systèmes de direction électronique (steer-by-Wire) doivent respecter des contraintes à la fois de fiabilité et de temps réel. Ce papier présente une approche intégrée pour évaluer à la fois les performances temporelles et la fiabilité comportemental

Safety Evaluation of Critical Applications Distributed on TDMA-Based Networks

Critical embedded systems have to provide a high level of dependability. In automotive domain, for example, TDMA protocols are largely recommended because of their deterministic behavior. Nevertheless, under the transient environmental perturbations, the loss of communication cycles may occur with a certain probability and, consequently, the system may fail. This paper analyzes the impact of the transient perturbations (especially due to Electromagnetic Interferences) on the dependability of systems distributed on TDMA-based networks. The dependability of such system is modeled as that of "consecutive-k-out-of-n:F" systems and we provide a efficient way for its evaluation

Design of automotive X-by-Wire systems

http://www.taylorandfrancis.com/X-by-Wire is a generic term referring to the replacement of mechanical or hydraulic systems, such as braking or steering, by electronic ones. In this chapter, we analyze the real-time and dependability constraints of X-by-Wire systems, review the fault-tolerant services that are needed and the communication protocols (TTP/C, FlexRay and TTCAN) considered for use in such systems. Using a Steer-by-Wire case-study, we detail the design principles and verification methods that can be used to ensure the stringent constraints of X-by-Wire systems

Quantitative Evaluation of the Safety of X-by-Wire Architecture subject to EMI Perturbations

The X-by-Wire systems in cars can only be accepted if they provide at least the same dependability than the traditional ones. In this paper we propose a new approach to evaluate the impact of the EMI perturbations on the dependability of an X-by-Wire architecture. The considered X-by-Wire architecture is distributed around a TDMA-like communication protocol. So a perturbation causes the loss of a communication cycle with a certain probability. The vehicle level failure is then defined as the consecutive loss of a certain number of communication cycles. Its reliability is modeled as that of the well-known consecutive-k-out-of-n:F systems. A case study, together with the EMI perturbations collected on the roads in France, is used to illustrate our approach

An Approach for the Assessment of System Upset Resilience

This report describes an approach for the assessment of upset resilience that is applicable to systems in general, including safety-critical, real-time systems. For this work, resilience is defined as the ability to preserve and restore service availability and integrity under stated conditions of configuration, functional inputs and environmental conditions. To enable a quantitative approach, we define novel system service degradation metrics and propose a new mathematical definition of resilience. These behavioral-level metrics are based on the fundamental service classification criteria of correctness, detectability, symmetry and persistence. This approach consists of a Monte-Carlo-based stimulus injection experiment, on a physical implementation or an error-propagation model of a system, to generate a system response set that can be characterized in terms of dimensional error metrics and integrated to form an overall measure of resilience. We expect this approach to be helpful in gaining insight into the error containment and repair capabilities of systems for a wide range of conditions

How a Diverse Research Ecosystem Has Generated New Rehabilitation Technologies: Review of NIDILRR’s Rehabilitation Engineering Research Centers

Over 50 million United States citizens (1 in 6 people in the US) have a developmental, acquired, or degenerative disability. The average US citizen can expect to live 20% of his or her life with a disability. Rehabilitation technologies play a major role in improving the quality of life for people with a disability, yet widespread and highly challenging needs remain. Within the US, a major effort aimed at the creation and evaluation of rehabilitation technology has been the Rehabilitation Engineering Research Centers (RERCs) sponsored by the National Institute on Disability, Independent Living, and Rehabilitation Research. As envisioned at their conception by a panel of the National Academy of Science in 1970, these centers were intended to take a “total approach to rehabilitation”, combining medicine, engineering, and related science, to improve the quality of life of individuals with a disability. Here, we review the scope, achievements, and ongoing projects of an unbiased sample of 19 currently active or recently terminated RERCs. Specifically, for each center, we briefly explain the needs it targets, summarize key historical advances, identify emerging innovations, and consider future directions. Our assessment from this review is that the RERC program indeed involves a multidisciplinary approach, with 36 professional fields involved, although 70% of research and development staff are in engineering fields, 23% in clinical fields, and only 7% in basic science fields; significantly, 11% of the professional staff have a disability related to their research. We observe that the RERC program has substantially diversified the scope of its work since the 1970’s, addressing more types of disabilities using more technologies, and, in particular, often now focusing on information technologies. RERC work also now often views users as integrated into an interdependent society through technologies that both people with and without disabilities co-use (such as the internet, wireless communication, and architecture). In addition, RERC research has evolved to view users as able at improving outcomes through learning, exercise, and plasticity (rather than being static), which can be optimally timed. We provide examples of rehabilitation technology innovation produced by the RERCs that illustrate this increasingly diversifying scope and evolving perspective. We conclude by discussing growth opportunities and possible future directions of the RERC program

Fault Tolerant Services for Safe In-Car Embedded Systems

http://www.taylorandfrancis.com/Due to the increasing criticality of the functions in terms of safety, embedded automotive systems must now respect stringent dependability constraints despite the faults that may occur in a very harsh environment. In a context where critical functions are distributed over the network, the communication system plays a major role. First, we discuss the main services and functionalities that a communication system should offer for easying the design of fault-tolerant applications in the automotive context. Then, we review the features of the protocols that are currently considered for being used and, finally, we highlight areas where developments are still needed

New trends in electrical vehicle powertrains

The electric vehicle and plug-in hybrid electric vehicle play a fundamental role in the forthcoming new paradigms of mobility and energy models. The electrification of the transport sector would lead to advantages in terms of energy efficiency and reduction of greenhouse gas emissions, but would also be a great opportunity for the introduction of renewable sources in the electricity sector. The chapters in this book show a diversity of current and new developments in the electrification of the transport sector seen from the electric vehicle point of view: first, the related technologies with design, control and supervision, second, the powertrain electric motor efficiency and reliability and, third, the deployment issues regarding renewable sources integration and charging facilities. This is precisely the purpose of this book, that is, to contribute to the literature about current research and development activities related to new trends in electric vehicle power trains.Peer ReviewedPostprint (author's final draft

Enabling Social Interaction Through Embodiment in ExCITE

No abstract availableThe emerging demographic trends toward an aging population involve an unflagging research of ways of assisting elderly people to stay independent for as long as possible. This means to be active at home and in the labour market, to prevent social isolation and promote societal inclusion. Both ICT and robotics technologies can contribute to help achieving these goals. This paper introduces the aims of the Ambient Assisted Living project ExCITE whose main objective is to enhance a robotic platform for telepresence with features enabling social interaction from a domestic environment to the outside world. The whole ExCITE project uses a user-centered approach hence it evolves around an intensive evaluation to be performed in situ, on a PanEuropean scale. An existing prototype, called Giraff, is to be deployed to targeted end-users, and refined taking into account outcome of the evaluation. This paper introduces the objectives of ExCITE and offers a description of its initial activities particularly focused on the user evaluation

Transportability of Trauma-Focused Cognitive Behavioral Therapy : A Case Study with Adolescents in a Residential Treatment Setting

Because of the increase in the numbers of adolescents presenting in residential care, the challenge and difficulty posed to therapists in treating this age-group, and the prevalence of chronic stress and complex trauma symptoms found in this population, the research conducted was a clinical case study investigating the transportability and effectiveness of using Trauma-Focused Cognitive Behavioral Therapy (TF-CBT), a manualized treatment format, with adolescent clients in a residential treatment setting. A doctoral candidate was trained to engage each of three residential clients in 12 individual sessions of TF-CBT. The Behavior Assessment System for Children (BASC), Children’s Depression Inventory (CDI), Jesness Behavior Checklist (JBC), Revised Children’s Manifest Anxiety Scale (RCMAS), Trauma Symptom Checklist for Children (TSCC), Working Alliance Inventory (WAI), were administered at pretest, mid-way through treatment, and at posttest to assess treatment outcome. A qualitative assessment of treatment outcome comparing pretest scores and posttest scores on measures were made, and a discussion of the treatment efficacy of TF-CBT with older adolescents in residential treatment was provided. Suggestions for future research of the application of TF-CBT with youth in a residential treatment setting are offered by the researcher. An empirical study proposal was devised to demonstrate the study\u27s application to a larger sample size