Model based Systems Engineering-A Unified Approach using UML

Dynamically controlled safety applications, passenger comfort, information and entertainment for operational convenience are the field of permanent innovation. In BMW’s high performance luxury segment’s vehicles, about 80 electronic control units are networked together to provide the driver with numerous features. To guarantee an appropriate level of quality within the allowed integration time of features, new and progressive techniques as well as notations are needed to support the early phases of development. The early phases of development include a maximum amount of potential to solve issues on the future development methodology. In addition to new notations reliably controlled integration processes for components with significantly different life-cycles including information management and change control are sketched. For these purposes BMW chose to utilize the Unified Modeling Language (UML) and to define its automotive-specific subset of UML. The structural part of the analysis model is specified by a state based specification notation to generate “executable requirements”. To support our methodology, domain specific and commercial tools have been tightly integrated to support a seamless development process. Effective information management and change control are based on a sound and seamless management of the projects’ requirements. Thus, the information model of the developed products is embedded in the requirements model. INTRODUCTION Though innovative features are key potentials to competitive advantage, their merit will be limited, if quality, cost and time-to-market constraints are not met. Customers’ wishes and requirements and the systems’ constraints set up the entirety of functional and non-functional requirements, that have to be met as a prerequisite for successful products. To be able to keep these requirements it has to be ensured, that they are completely elicited and documented to know them in their entirety, without ambiguities, incorrectness or contradictions, in an up-to date status. The requirements model evolves during product development, i.e. requirements continuously change, are updated, deleted or new ones are created. To be able to control the “magic triangle” of quality, cost and time constraints reliably, these changes have to be integrated into the current requirements model, their impact has to be analyzed and evaluated, tradeoffs have to be carried out, decisions have to be made and to be documented (EIA et al. 1999). This paper presents results of our research towards an integrated development methodology and management principles of the requirements model (functional and non-functional) with notations of the automotive modeling language AML in terms of processes, methods and tools. The selected tools for the targeted process are Telelogic’s UML Suite (Telelogic 1999) for a model based requirements documentation, ETAS’s ASCET-SD (ETAS 1998) for the specification of continuous as well as discrete and hybrid systems. All of these tools are underpinned by QSS’s DOORS (Quality Systems & Software 1998) for managing the complete set of requirements. For a better illustration of our methodology a prototypical run through our new development process is sketched in application to a running example. The example focuses on the sequencing development activities in the requirements engineering phase to elaborate a requirements model for the electronic control unit of an interior light control within a car. The paper is organized as follows. The section Requirements Engineering describes the requirements engineering process for electronic control units including all notations and generated products. Essential steps of this process are illustrated by an example, the development of the interior lighting. Section Requirements Management introduces the basic concepts of requirements management and their deployment within the requirements engineering process. Finally, section Conclusion gives a survey of our work on an integrated tool suite, which is underpinning the described processes. REQUIREMENTS ENGINEERING Common development processes of electronic control units in the field of automotive systems are 1 The AML comprises a subset of UML and ASCET-SD