Approach for model-based requirements engineering for the planning of engineering generations in the agile development of mechatronic systems

The crucial factor for a successful usage of modeling approaches of systems engineering is the interaction of language, method, and tool. For this, specific challenges arise for the application of MBSE in agile requirements engineering. From observations in agile development practice at a machine tool manufacturer, the challenges for model-based requirements engineering are described and each is assigned to its critical aspect of modeling: The language must formally represent the requirements data model, especially for planning engineering generations. The tool must support collaborative, interdisciplinary cooperation, and consider the dynamics of the requirements model during the development process. The method must individually support the requirements engineering activities, which are carried out several times in a sprint during the development process and must enable a target-oriented process for bundling the requirements into engineering generations. Taking these demands into account, an approach is then presented providing activity-based views in conjunction with activity steps based on a consistent ontology for the description of product requirements and verification activities. The activity steps are composed in activity patterns and support the user in making use of the views for modeling requirements for the engineering generations. The approach is implemented in the software JIRA at a machine tool manufacturer. The subsequent evaluation shows that the approach is used in development practice and offers the potential to plan engineering generation systematically and comprehensibly and to ensure a regular review of the implemented requirements

Assessing the Risk due to Software Faults: Estimates of Failure Rate versus Evidence of Perfection.

In the debate over the assessment of software reliability (or safety), as applied to critical software, two extreme positions can be discerned: the ‘statistical’ position, which requires that the claims of reliability be supported by statistical inference from realistic testing or operation, and the ‘perfectionist’ position, which requires convincing indications that the software is free from defects. These two positions naturally lead to requiring different kinds of supporting evidence, and actually to stating the dependability requirements in different ways, not allowing any direct comparison. There is often confusion about the relationship between statements about software failure rates and about software correctness, and about which evidence can support either kind of statement. This note clarifies the meaning of the two kinds of statement and how they relate to the probability of failure-free operation, and discusses their practical merits, especially for high required reliability or safety

Functional Requirements-Based Automated Testing for Avionics

We propose and demonstrate a method for the reduction of testing effort in safety-critical software development using DO-178 guidance. We achieve this through the application of Bounded Model Checking (BMC) to formal low-level requirements, in order to generate tests automatically that are good enough to replace existing labor-intensive test writing procedures while maintaining independence from implementation artefacts. Given that existing manual processes are often empirical and subjective, we begin by formally defining a metric, which extends recognized best practice from code coverage analysis strategies to generate tests that adequately cover the requirements. We then formulate the automated test generation procedure and apply its prototype in case studies with industrial partners. In review, the method developed here is demonstrated to significantly reduce the human effort for the qualification of software products under DO-178 guidance