(An) integrated environment of software development and V&V for PLC based safety-critical systems

Abstract

To develop and implement a safety-critical system, the requirements of the system must be analyzed thoroughly during the phases of a software development``s life cycle because a single error in the requirements can generate serious software faults. We therefore propose an Integrated Environment (IE) approach for requirements which is an integrated approach that enables easy inspection by combining requirement traceability and effective use of a formal method. For the V&V tasks of requirements phase, our approach uses software inspection, requirement traceability, and formal specification with structural decomposition. Software inspection and the analysis of requirements traceability are the most effective methods of software V&V. Although formal methods are also considered an effective V&V activity, they are difficult to use properly in nuclear fields, as well as in other fields, because of their mathematical nature. We also propose another Integrated Environment (IE) for the design and implementation of safety-critical systems. In this study, a nuclear FED-style design specification and analysis (NuFDS) approach was proposed for PLC based safety-critical systems. The NuFDS approach is suggested in a straightforward manner for the effective and formal specification and analysis of software designs. Accordingly, the proposed NuFDS approach comprises one technique for specifying the software design and another for analyzing the software design. In addition, with the NuFDS approach, we can analyze the safety of software on the basis of fault tree synthesis. To analyze the design phase more effectively, we propose a technique of fault tree synthesis, along with a universal fault tree template for the architecture modules of nuclear software. Various tools have been needed to make software V&V more convenient. We therefore developed four kinds of computer-aided software engineering tools that could be used in accordance with the software``s life cycle to support the...