Dr. rer. nat.

Weiß, Gereon

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  • Publication
    Verifying network performance of cyber-physical systems with multiple runtime configurations
    ( 2015)
    Manderscheid, Martin
    ;
    Weiß, Gereon
    ;
    Knorr, Rudi
    Modern Cyber-Physical Systems (CPS) must increasingly adapt to changing contexts, like smart cars to changing driving conditions. Thus, design approaches are facing a rapidly growing number of network runtime configurations. With recent approaches this problem can be solved for design space exploration (DSE) by analyzing the network performance of single configurations which are intended to represent the entire runtime variability space. This technique can be applied for DSE since the latter only intends to find an optimized system setup. Yet it does not meet the requirements of network verification, since it does not necessarily find the worst-case for all applications. To solve this, we developed an integrated model, which allows describing runtime variability in the network performance model with a0-1 linear-fractional program. Thus, we can cover entire runtime variability spaces without analyzing every single network runtime configuration. Although the approach utilizes heuristics, it still guarantees worst-case results. We can show that in comparison to state-of-the-art methods our approach scales for large automotive systems with multiple network configurations. Moreover, our evaluation results highlight the superior capabilities of our method with respect to accuracy and computation time.
  • Publication
    Parameterization of fail-operational architectural patterns
    ( 2015)
    Oliveira da Penha, Dulcineia
    ;
    Weiß, Gereon
    In today's cyber physical systems, adaptability concepts can be used to fulfill fail-operational requirements while enabling optimized resource utilization. However, the applicability of such concepts highly depends on the support for the engineering during system development. We propose an approach to cope with the challenges of fail-operational behavior of CPS in which engineers are supported by design concepts for realizing safety, reliability, and adaptability requirements through the use of architectural patterns. The approach allows expressing concepts for fail-operational behavior at the software architecture level. By our approach, the effort for developing adaptive CPS can be kept low by utilizing fail-operational architectural patterns for general and reoccurring safety-relevant mechanisms. This is demonstrated by an application to an automotive case system.
  • Publication
    Pattern-based approach for designing fail-operational safety-critical embedded systems
    ( 2015)
    Penha, Dulcineia
    ;
    Weiß, Gereon
    ;
    Stante, Alexander
    To deal with fail-operational (FO) requirements intoday's safety-critical networked embedded systems (SCNES), engineers have to resort to concepts such as redundancy, monitoring, and special shutdown procedures. Hardware-based redundancy approaches are not applicable to many embedded systems domains (e.g., automotive systems), because of prohibitive costs. In this scenario, adaptability concepts can be used to fulfill these FO requirements while enabling optimized resource utilization. However, the applicability of such concepts highly depends on the support for the engineering during system development. We propose an approach to cope with the challenges of fail-operational behavior of SCNES in which engineers are supported by design concepts for realizing safety, reliability, and adaptability requirements through the use of architectural patterns. The approach allows expressing FO concepts at the software architecture level. This lowers the effort for developing SCNES by utilizing generic patterns for genera land reoccurring mechanisms.
  • Publication
    Context modeling for dynamic configuration of automotive functions
    ( 2013)
    Weiß, Gereon
    ;
    Grigoleit, Florian
    ;
    Struss, Peter
    Current vehicles are usually equipped with an abundance of advanced driver assistant systems. Only a limited number of them can really be active permanently. This motivates our goal of providing the car with the means necessary to dynamically adapt the set of active functions to its current requirements. In this paper, we present a generic context modeling approach suitable for dynamic configuration of automotive functions. The demonstration of the feasibility of the proposed solution and evaluation of its effectiveness was based on a simulated prototypical system configuration. The simulations yielded to a significant reduction in average function activity of an exemplary car system. Depending on the provided context parameters, a reduction of up to 24% was achieved.