Thomas Peikenkamp

Using contract-based component specifications for virtual integration testing and architecture design

We elaborate on the theoretical foundation and practical application of the contract-based specification method originally developed in the Integrated Project SPEEDS [11], [9] for two key use cases in embedded systems design. We demonstrate how formal contract-based component specifications for functional, safety, and real-time aspects of components can be expressed using the pattern-based requirement specification language RSL developed in the Artemis Project CESAR, and develop a formal approach for virtual integration testing of composed systems based on such contract-specifications of subsystems. We then present a methodology for multi-criteria architecture evaluation developed in the German Innovation Alliance SPES on Embedded Systems.

Metamodels in Europe: Languages, Tools, and Applications

This article provides an overview of current efforts in Europe for using metamodeling in the integrated development of critical systems such as automotive electronics. It distinguishes between lightweight versus heavyweight approaches, surveys a number of related current European projects, and gives details about the Speeds project to illustrate the role of metamodeling-driven system engineering.

Compositional Performability Evaluation for STATEMATE

This paper reports on our efforts to link an industrial state-of-the-art modelling tool to academic state-of-the-art analysis algorithms. In a nutshell, we enable timed reachability analysis of uniform continuous-time Markov decision processes, which are generated from STATEMATE models. We give a detailed explanation of several construction, transformation, reduction, and analysis steps required to make this possible. The entire tool flow has been implemented, and it is applied to a nontrivial example

Model Based Importance Analysis for Minimal Cut Sets

We show how fault injection together with recent advances in stochastic model checking can be combined to form a crucial ingredient for improving quantitative safety analysis. Based on standard design notations (Statecharts) annotated with fault occurrence distributions we compute to what extent certain fault configurations contribute to the probability of reaching a safety-critical state.

Towards a unified model-based safety assessment

The increase of complexity in aircraft systems demands for enhanced analysis techniques. Methods are required that leverage the burden of their application by reusing existing design and process information and by enforcing the reusability of analyses results allowing early identification of designs weak points and check of design alternatives.This report elaborates on a method that assumes a system specification in an industrial standard notation and allows to perform several formal safety analyses. Based on a collection of failure models and means of specifying safety requirements, the techniques produce results along the lines of traditional methods. We show how to combine traditional techniques, required by the AerospaceRecommendedPractice (SAE-ARP) standards, likeFaultTree Analysis, Failure Mode and Effect Analysis and Common Cause Analysis and also how to automate most of the analysis activities. The methods described in this paper can be used as means to support the Certification process.

Towards cross-domains model-based safety process, methods and tools for critical embedded systems: the CESAR approach

The CESAR project1 aims at elaborating a Reference Technology Platform usable across several application domains (Aeronautics, Automotive, Industrial Automation, Railway and Space) for the cost effective development and validation of safety related embedded systems. Safety and, more generally, dependability are therefore major topics addressed by the project. This paper focuses on the work performed on safety requirements and approaches to be supported by a common Reference Technology Platform. We analyse and compare the industrial practice, applicable standards and state of the art so as to identify which and how safety views should be supported. We focus in particular on the major axes investigated by the project, formal model-based techniques for requirements engineering and component-based engineering. Preliminary realisations and case studies confirm the interest and provide refined requirements for the final version of the platform.

Evaluation of drivers interaction with assistant systems using criticality driven guided simulation

Advanced Driver Assistance Systems (ADAS) operate more and more autonomously and take over essential parts of the driving task e.g. keeping safe distance or detecting hazards. Thereby they change the structure of the drivers task and thus induce a change in drivers behavior. Nevertheless it is still the driver who is ultimately responsible for the safe operation of the vehicle. Therefore it is necessary to ensure that the behavioral changes neither reduce the controllability of the vehicle nor the controllability of the hazardous events. We introduce the Threshold Uncertainty Tree Search (TUTS) algorithm as a simulation based approach to explore rare but critical driver behavior in interaction with an assistance system. We present first results obtained with a validated driver model in a simple driving scenario.

A method for guided hazard identification and risk mitigation for offshore operations

One of the effects of the radically changing energy market is that more and more offshore wind turbines are being constructed. To meet the increasing demand for renewable energy, many new companies with different levels of experience are entering the market. As the construction and maintenance of large offshore wind farms is a complex task, safety aspects of these operations are of crucial importance to avoid accidents. To this end, we introduce a method that assists in (1) identifying and precisely describing hazards of a scenario of an offshore operation, (2) quantifying their safety impact, and (3) developing risk mitigation means. Based on a guided hazard identification process, a formalization of hazardous scenarios will be proposed that unambiguously describes the risks of a given offshore operation. We will demonstrate the feasibility of our approach on a specific offshore scenario.

An Extended Gradient Model for NUMA Multiprocessor Systems

In this paper, we present the design and implementation of an effective and scalable dynamic load balancing system for Non-Uniform Memory Access (NUMA) multiprocessors where load balancing is a key issue to achieve adequate efficiency. The proposed load balancing algorithm extends the well-known gradient model to enhance its applicability in a wide range of multiprocessor systems and to improve the overall system performance. A comparative performance study between the two models based on the preliminary simulation results is also reported in the paper.

A Formal Semantics for Traffic Sequence Charts.

This paper paves the way for a future scenario catalog-based approach to acceptance testing for highly autonomous vehicles by providing a rigorous formal semantics for a visual specification language of traffic sequence charts to be used for building the scenario catalog. It builds on our previous work on Live Sequence Charts [2] that defines a semantics sufficiently rich to cover both the requirement analysis phase and the specification phase for highly autonomous vehicles. This formal semantics provides the basis for tool support, in particular supporting the future V&V environment for autonomously driving cars under development by the German automotive industry.