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PreHaz: A Premortem Functional Safety Hazard Assessment Technique for Autonomous Vehicles

DISTek Integration-Daniel Aceituna
Published 2019-06-14 by SAE International in United States
When performing functional safety hazard assessments, the challenge is anticipating all the things that can go wrong during a system’s operation. Hazard assessment tends to be performed in an ad hoc (where do I begin assessing?) and open-ended (when do I stop assessing?) manner. It is difficult for humans to factor in all the variables that affect a system’s nominal interaction with the environment and then predict all the combinational behaviors (good or bad) resulting from those variables. Quite often, after the system is built, a hazardous situation will occur that no one expected, and perhaps even assumed improbable. At those times engineers may employ a postmortem and realize that, with enough forethought, the hazard could have been assessed and anticipated. In contrast to the postmortem, there is the premortem, which tries to assess what can go wrong, before it actually occurs. This paper introduces a technique based on the premortem that can be applied to the development of a product and, in particular, to the assessment of hazardous situations that could arise from the…
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A Means of Assessing the Entire Functional Safety Hazard Space

DISTek Integration Inc.-Daniel Aceituna
Published 2017-09-19 by SAE International in United States
The goal behind Functional Safety is to anticipate the potential hazard scenarios (a.k.a. harm sequences) that a system may produce and address those scenarios in such a way as to mitigate or even eliminate them. A major challenge in determining hazard scenarios is trying to assess an adequate amount of scenarios, considering the large size of a hazard space. Typically assessing the entire hazard space is difficult to achieve, resulting in the possibility of overlooking some critical scenarios that can result in harm to either system operators, system by-standers, or both. In this paper we will explore a rule-based approach for concisely describing hazard scenarios, which could potentially enable us to examine the entire hazard space in a short amount of time. Our approach, called Hazard Space Analysis, combines three key activates: determining hazard scenarios, assigning a risk factor to those scenarios, and mapping those hazard scenarios directly to safety rules. We will detail the approach, show how the approach could be automated, and present a simple aviation related example that demonstrates the approach's potential…
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Elicitation Practices That Can Decrease Vulnerability to Off-Nominal Behaviors: Lessons from using the Causal Component Model

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

DISTek Integration Inc.-Daniel Aceituna
  • Journal Article
  • 2016-01-8109
Published 2016-09-27 by SAE International in United States
When specifying an embedded system-to-be, a key consideration is how the embedded system will interact with its operating environment. Of particular concern is the system's vulnerability to Off-Nominal Behaviors (ONB) from human interaction. ONB vulnerability can result in human operators placing the system in an undesired state through an unforeseen sequence of events. This, in turn, can have an adverse effect on the system’s quality. Reducing ONB vulnerability can be challenging because human behavior can be unpredictable and stakeholders have a natural tendency to assume the system will be used in a predictable, nominal, manner. One approach to reducing ONB vulnerability is to specify the system as "fool-proof" as possible, during the requirements phase, where access to domain experts is at its most convenient. This also raises awareness of potential ONB problems prior to the design phase, rather than after implementation where, quite often, ONBs are addressed through off-nominal testing. This paper presents a checklist of requirement elicitation questions that can result in lower ONB vulnerability. The checklist is derived from lessons learned from using…
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Survey of Concerns in Embedded Systems Requirements Engineering

SAE International Journal of Passenger Cars - Electronic and Electrical Systems

DISTek Integration, Inc.-Daniel Aceituna
  • Journal Article
  • 2013-01-2403
Published 2013-09-24 by SAE International in United States
Requirements engineering is an important part of the software development process. There are various challenges associated with the elicitation, analysis, documentation, and validation of requirements, and these challenges can be more pronounced in embedded software systems, where a number of characteristics, unique to these systems, must be addressed. This paper will examine the unique concerns surrounding the requirements engineering of embedded software systems, including the need to elicit, specify, and validate, interrupts and exceptions, concurrency, and timing. We will then survey and examine some of the current requirements engineering research that can address these concerns. Finally, we will consider whether some of the requirements engineering concerns and practices conceived for, and utilized in the Information Technology (IT) domain, can be beneficial to the development of embedded systems.
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Algorithm Design Using LabVIEW

Phoenix International-Daniel Aceituna
Published 2002-03-19 by SAE International in United States
In the arena of software development, there are many tools. However, one area of the development process where tools are wanting is in the area of designing and modeling algorithms. An algorithm is a set of instructions for solving a problem. And during the design of an algorithm, the details of a particular programming language can be distracting and thus obscure the simplicity of the solution. The goal of this paper is to introduce the reader to an “off-the-shelf” means of developing algorithms in both a faster and more intuitive way. The proposed methodology utilizes LabVIEW, a graphical programming language normally used for data acquisition and automating production testers.
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