Model-based systems engineering with requirements variability for embedded real-time systems

Product Line Engineering (PLE) offers the benefits of reducing costs and time to market by reusing requirements and components. Current PLE methods, however, mainly focus on the software aspects and are lacking in support for many system level concerns like physical and non-functional require-ments (Quality of Service attributes) that play an important role in the development of Embedded Real-Time Systems (RTS). This paper proposes a new method to support a combination of variability modelling (a key feature of PLE) and model-based requirement engineering (in SysML) for Embedded RTS. It provides four main contributions: 1. it extends the Orthogonal Variability Model (OVM) to support the separation of function-al, physical and non-functional variability; 2. it proposes a mechanism for the evolution of variability; 3. stakeholders' specifications for variable requirements are extended by the proposed approach; 4. it increases the consistency of system models by directly using SysML Activity Diagrams and Block Definition Diagrams as a base model for refining variability models for requirement representation. The proposed method is illustrated by an Aircraft Engine Control System case study.