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Auflistung nach Autor:in "Kaiser, Bernhard"

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  • Konferenzbeitrag
    Lightweight contracts for safety-critical automotive systems
    (INFORMATIK 2015, 2015) Kaiser, Bernhard; Sonski, Stefan; Buono, Suryo; Petersen, Hauke; Zander, Justyna
    Complex automotive systems are composed of subsystems and components in a deep hierarchy, often designed by different development partners or reused from preexisting projects. It is therefore a challenging task to break down requirements into sub-requirements fitting the scope of the subsystems and to simultaneously demonstrate that the integrated system fulfills both functional and safety requirements specified on the top-level. Contract-based development is a popular approach for breaking down requirements onto components by means of assumptions and guarantees. However, most current approaches are based on a formal semantics and therefore limited in their expressive power and their acceptance by practitioners from automotive industries. We propose a semi-formal approach that allows specifying assumptions and guarantees at component interfaces in a language with well-defined syntax, but leaving the verification of fulfillment of the contract by a component to expert decision. However, some of the relevant refinement relations can be formalized and automatically checked. We describe our prototypical Eclipse tool that allows the annotation of components with assumptions and guarantees, and the partial checking of the decomposition. We show the applicability by a case study of an automotive electric drive system.
  • Konferenzbeitrag
    Systematic Refinement of CPS Requirements using SysML, Template Language and Contracts
    (Modellierung 2018, 2018) Grabowski, Markus; Kaiser, Bernhard; Bai, Yu
    In these day we encounter the transition from traditional closed and restricted-purpose embedded systems towards networked Cyber-Physical Systems. This applies to many industries, but in particular to the automotive industry, where assistance and automated driving functions are shaped out of complex combinations of functions and electronic control units, and even the car as a whole becomes part of a larger network of many vehicles plus infrastructure. And still, verifiable assertions must be available in the end to satisfy the safety case. The specification skills in industry often turn out to be insufficient. Even today, the mandatory V-model is hard to apply in practice and expressing appropriate requirements and refinements along with the evolution of the architecture is a hard thing to do. When development becomes agile and centered around component reuse, things become even more complex. We report about our experience with the application of contract-based development and explain keystones of our approach. We present a new template language called SSPL that allows the specification of requirements and assertions on every system architecture level and show how contract-based requirements refinement can go hand in hand with architecture refinement in SysML. We further present our Eclipse-based tool SAVONA that enables practical application of the approach.