The MobSTr dataset contains a number of artifacts for an autonomous driver assistance system, ranging from textual requirements to models for system design and models relevant to safety assurance. The artifacts provided are connected with traceability links created and managed with Eclipse Capra, an open source traceability management tool. The dataset builds upon a custom traceability information model that provides type safety and semantics for the trace links. MobSTr is intended for researchers that work on software and systems traceability as well as on model-based safety assurance. It is already being used in a number of studies, including research on trace link consistency, change impact analysis, and automated analysis of safety and timing requirements.

The analysis of real-time properties is crucial in safety critical areas. Systems have to work in a timely manner to offer correct services. The analysis of timing properties is particularly difficult for distributed systems when complex interferences between individual tasks can occur. Considering only critical instances, as analytic approaches do, may deliver pessimistic results leading to higher production costs. In previous works we introduced a state-based approach to validate task-and end-to-end deadlines for distributed systems. To improve scalability and reduce the analysis time, the approach computes the state spaces of the individual resources in a compositional fashion. For this, abstraction and composition operations were defined to remove those parts of the inputs of resources which have no influence on the response times of the allocated tasks. In this work, a new abstraction technique is introduced for scenarios where event bursts occur. Further, we extend our approach for systems with cyclic dependencies among the resources. We evaluate our approach on a set of example scenarios and compare the results with the state-of-the-art tool Uppaal.

The analysis of real-time properties is crucial in safety critical areas, and is particularly difficult for distributed systems as complex interferences between tasks of different priorities can occur. In previous works we have introduced a state-based analysis approach to validate end-to-end deadlines for distributed systems, where the state spaces of all resources, such as processors and buses, are computed in a compositional fashion. For this, abstraction and composition operations were defined to adequately handle task and resource dependencies. During the design process of a system changes occur typically on both the specification and implementation level, such that already performed analyses of the system have to be repeated. In this work, we define a methodology to adequately handle such changes and to determine the minimal part of the affected architecture. For this, we define an appropriate refinement relation between state spaces of the resources. We use contracts to further reduce the re-validation effort. This check takes place at a higher design level, where only the specification is considered.

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.

The SPEEDS project is aimed at making rich components models (RCM) into a mature framework in all phases of the design of complex distributed embedded systems. The RCM model is required to be expressive enough to cover the entire development process from requirements to code through design, and also capture both functional and non-functional aspects. In this paper we propose a language-based framework for real-time component interfaces in SPEEDS that is suitable at the ECU layer when a target processor has been identified, and WCET analysis done. We assume a discrete time model.

This paper addresses the problem of assigning tasks to embedded control units. The units are considered to be connected via a bus, and tasks may already be deployed onto the units. To save costs, the objective is to insert as many new tasks onto the system as possible. In this setting, to support early design decisions, we present an approximative and fast pre-analysis of the system. We introduce spare-time analysis and the analysis of maximal allowed worst-case execution time to simplify the problem and to achieve a fast solving algorithm, which we implement as mixed-integer linear problem. We conduct experiments to investigate the scalability of the approach with the result that for input sizes of up to 160 tasks with up to 50% not-yet-deployed tasks a solution is found in many cases within reasonable time, our machine needs in the average case 150s. With a reference example, taken from literature, we compare our approach with a similar method and show that our approach is faster.

Analysis and verification of safety critical systems is inevitable to assure functional and temporal correctness. For checking temporal system behaviour, real-time scheduling analysis has been proved to be an efficient method. As an analytical method, real-time scheduling relies on rather simple task network models mostly ignoring functional behaviour in order to remain computable and efficient. Functional and temporal system behaviour however are often closely related. By abstracting from functional behaviour, scheduling analysis often results in large over-approximation for such systems. We propose a task network model providing extensions to describe also functional system behaviour. The main elements are explicit data objects and tasks with internal states and data dependant executions. Since there are no analytical methods known to be available for such extended models we propose an analysis based on a combination of model-checking and testing. Although this technique does not provide exhaustive verification, it is a first step towards time-accurate analysis of complex realtime systems. Moreover, the approach provides a convenient way to check systems against functional and temporal requirements in contrast to analytical methods that are usually restricted to simple temporal properties like deadlines.

We present a SAT-based approach to the task and message allocation problem of distributed real-time systems with hierarchical architectures. In contrast to the heuristic approaches usually applied to this problem, our approach is guaranteed to find an optimal allocation for realistic task systems running on complex target architectures. Our method is based on the transformation of such scheduling problems into nonlinear integer optimization problems. The core of the numerical optimization procedure we use to discharge those problems is a solver for arbitrary Boolean combinations of integer constraints. Optimal solutions are obtained by imposing a binary search scheme on top of that solver. Experiments show the applicability of our approach to industrial-size task systems, which are mapped to heterogeneous hierarchical hardware architectures

We present a SAT-based approach to the task and message allocation problem of distributed real-time systems. In contrast to the heuristic approaches usually applied to this problem, our approach is guaranteed to find an optimal allocation for realistic task systems running on complex target architectures. Our method is based on the transformation of such scheduling problems into nonlinear integer optimization problems. The core of the numerical optimization procedure we use to discharge those problems is a solver for arbitrary Boolean combinations of integer constraints. Optimal solutions are obtained by imposing a binary search scheme on top of that solver. Experiments show the applicability of our approach to industrial-size task systems.