Characterizing the Identity of Model-based Safety Assessment: A Systematic Analysis

Model-based safety assessment has been one of the leading research thrusts of the System Safety Engineering community for over two decades. However, there is still a lack of consensus on what MBSA is. The ambiguity in the identity of MBSA impedes the advancement of MBSA as an active research area. For this reason, this paper aims to investigate the identity of MBSA to help achieve a consensus across the community. Towards this end, we first reason about the core activities that an MBSA approach must conduct. Second, we characterize the core patterns in which the core activities must be conducted for an approach to be considered MBSA. Finally, a recently published MBSA paper is reviewed to test the effectiveness of our characterization of MBSA

Airspace Integration of New Entrants and Safety Risk Management Models

In recent years, the demand for airspace access of Unmanned Aerial Systems (UAS) increased significantly and is continuously increasing for different altitude-types UAS. A similar evolution is expected from Commercial Space Operations (CSO) in the next years. These aviation/aerospace systems will need to be seamlessly integrated into the National Airspace System (NAS), at their operational altitude levels, and accounted for from all perspectives, including proactively addressing their safety hazards. This thesis captures the requirements for the new entrants’ integration, and then identifies and analyzes the safety risks added to the NAS operations by its new entrants, the future omnipresent UAS on different NAS levels, and the coming CSO age. Methodologies such as Functional Hazard Analysis, Subsystem and System Hazard Analysis, and Safety Risk Management are explored and integrated into the airspace new entrants’ framework and models. In addition, techniques such as state-machine modeling and simulation are used on an identified use case of UAS operations in crowded airspace

Metodologia para teste e análise de degradação de desempenho em protocolos de comunicação intra-veiculares

Considerar os efeitos de falhas e interferências que afetam as redes intra-veiculares desde o projeto dos seus sistemas de controle tornou-se fundamental, pois, a complexidade da eletrônica embarcada, o aumento do fluxo de informação e também as possibilidades de ataques maliciosos, tornaram o projeto destes sistemas uma tarefa cada vez mais complexa. Neste contexto, a presente tese visa explorar formas de integrar e modelar os efeitos de degradação causados por diferentes tipos de falhas que afetam os protocolos de comunicação, na interconexão das unidades de controle eletrônicas (ECUs). Dentre estas falhas, a pesquisa destaca o estudo aprofundado dos transientes elétricos rápidos – EFT, que degradam o desempenho e geram efeitos como perda de pacotes e atrasos de comunicação. Desta forma, contribui-se com uma metodologia para o tratamento de falhas em sistemas críticos de tempo real, desde as fases iniciais do projeto, utilizando a modelagem orientada a aspectos para modelar e especificar requisitos do sistema, de acordo com características transversais dos requisitos não funcionais relacionados a falhas. Para a definição dos requisitos não funcionais, esta pesquisa usa como base o framework RTFRIDA (Real-Time From Requirements to Design using Aspects), o qual foi estendido para agregar com mais detalhes a modelagem de falhas. Para fins de validação da metodologia foi desenvolvido um mecanismo de diagnóstico de degradação de desempenho, o qual foi integrado a um sistema de controle de suspensão ativa. O estudo foi avaliado em diferentes cenários de carga da rede e com injeções de falhas usando dois tipos de hardwares que seguem normas de teste usadas na indústria. Os resultados evidenciaram a aplicabilidade da metodologia, com a modelagem de um mecanismo de diagnóstico que detectou e registrou os distúrbios de desempenho nos cenários estudados. As análises enfatizam a degradação de desempenho acentuada registrada com as injeções EFT de maior amplitude de tensão e menor tempo de rajada, com carga de ocupação da rede acima de 30%. Os experimentos avaliaram o desempenho dos atuais protocolos de comunicação, com melhores resultados obtidos em FlexRay e CAN-FD, o que confirma a evolução dos protocolos para atender as recentes demandas de desempenho da indústria automotiva.Embedded computing applications are increasingly demanding performance and reliability because these factors are critical to the safety of real-time systems. Reliability aspects in design phases is a fundamental point of many researches because with the increase of embedded electronics, network data transmission and also possibilities of attacks on them, make the design of these systems an increasingly complex task. The present thesis aims to explore and correlate different fault types that degrade vehicular communication protocols performance used to interconnect embedded control units (ECUs). Among these faults, the electrical fast transients - EFT are highlighted, since they generate effects such as packet loss and communication delays. Thus, a methodology based on aspect-oriented modeling concepts, in real-time critical systems is proposed, to model and specify system requirements according to cross-cutting concerns of non-functional requirements related to faults. For non-functional requirements specification, this work is based on RT-FRIDA (Real-Time From Requirements to Design using Aspects) framework, which was be extended for fault modeling. Thus, the novel methodology allows fault modeling following the aspect-oriented principles from the early design phases. For the methodology validation purposes, a performance degradation diagnostic mechanism was developed, which was integrated into an active suspension control system. The study was evaluated in different network busload scenarios and with fault injections using two hardware types, certified by standards used in the automotive industry. The results present that the developed mechanism detected performance disturbances, recording occurrence data in the studied scenarios. The analyzes emphasize the best performance degradation observed with EFT injection of higher voltage amplitude, shorter burst time, and busload above 30%. The experiments evaluated the performance of current communication protocols, with better results obtained in FlexRay and CAN-FD, which confirms the protocol’s evolution to meet the recent performance demands of the automotive industry

A Framework for Model-Based Dependability Analysis of Cyber-Physical Systems

International audienc