A CNL for requirements as the basis to automate tasks of critical system development

Requirements play a key role in the airborne software development process. They serve as basis for verification and validation (V&V) during the system development. Requirements are in general specified in natural language. In this way, they are prone to misinterpretations and they have limited capacity of automatic processing, which in turn result in additional effort during system development. We propose a Controlled Natural Language (CNL) for specifying system requirements. The CNL specification is a formal representation of the requirements and it is used in an approach to automatically generate both system models and test cases. System models are used to verify the specified behavior of the system, and test cases are used to verify the system's functionality. We developed prototypes to automate the generation of both model and test cases, based on requirements defined in the CNL. A fly-by-wire system is used in the examples of our approach. The initial results show gains of effort.