Managing Variability in SysML Models of Automotive Systems

Abstract: Organizations developing software-intensive systems inevitably face increasing complexity of developed products, mainly due to rapid advancements in all domains of technology. Many such organizations are considering model-based systems engineering (MBSE) practices to cope with the increasing complexity. The use of models, as a central role during product design, promises to provide benefits such as enhanced communication among system stakeholders, continuous verification, improved design integrity, traceability between requirements and system artifacts and many more. Additionally, products are often built in many variants. That is especially obvious in the automotive domain, where customers have the ability to configure vehicles with hundreds of configuration options. To deal with the variability, a product line engineering approach is often used. It allows the development of a family of similar software-intensive systems that share a common base while being adapted to individual customer requirements.In this thesis, the overall goal is to evaluate and facilitate the combination of the two mentioned approaches, model-based systems engineering and product line engineering, in an industrial environment. To achieve the main thesis goal, it was divided into three separate research goals.The first goal was to identify challenges when applying an annotation-based approach for variant management in SysML models on a use case provided by Volvo Construction Equipment. The aim was to identify and understand challenges when using existing tool support to manage variants in implementation artifacts of existing products. The second research goal was to identify reuse-related challenges in the ``clone-and-own'' based development process of Volvo CE. Moreover, we assess the effects of model-based product line engineering on the identified challenges. Lastly, the third research goal was to develop an approach for consistency checking between variability- and SysML system models. To achieve that, we develop an integrated tool chain for model-based product line engineering that allows the integration of variable artifacts, which are not documented in system models, into the development process. Secondly, we define and develop an approach for consistency checking between variability models that describe the system in terms of features and implementation models that describe how variability is implemented in the product itself, since such support does not exist in current state of the art tools.In conclusion, based on the results from the results of case studies at Volvo CE, it was shown that model-based product line engineering has the potential to improve communication and highlight implications of variability to stakeholders (e.g. to non-technical staff), improve traceability between variability in requirements and variability in design and implementation, improve consistency through constraints between variants and automate repetitive activities.In other words, it shows potential for improving product quality while reducing the development lead time. However, the evaluation and measurement of improvement will be left for future work as measuring the product quality and lead time requires an organizational roll out of model-based product-line engineering.