Synthesis of functional models from use cases using the system state flow diagram: A nested systems approach

noThe research presented in this paper addresses the challenge of developing functional models for complex systems that have multiple modes of operation or use cases. An industrial case study of an electric vehicle is used to illustrate the proposed methodology, which is based on a systematic modelling of functions through nested systems using the system state flow diagram (SSFD) method. The paper discusses the use of SSFD parameter based state definition to identify physical and logical conditions for joining function models, and the use of heuristics to construct complex function models

Integrating formal methods into medical software development : the ASM approach

Medical devices are safety-critical systems since their malfunctions can seriously compromise human safety. Correct operation of a medical device depends upon the controlling software, whose development should adhere to certification standards. However, these standards provide general descriptions of common software engineering activities without any indication regarding particular methods and techniques to assure safety and reliability. This paper discusses how to integrate the use of a formal approach into the current normative for the medical software development. The rigorous process is based on the Abstract State Machine (ASM) formal method, its refinement principle, and model analysis approaches the method supports. The hemodialysis machine case study is used to show how the ASM-based design process covers most of the engineering activities required by the related standards, and provides rigorous approaches for medical software validation and verification

Validating the requirements and design of a hemodialysis machine using iUML-B, BMotion Studio, and co-simulation

We present a formal specification of a hemodialysis machine (HD machine) using Event-B. We model the HD machine using iUML-B state-machines and class diagrams and build a corresponding BMotion Studio visualisation. We focus on validation using (i) diagrams to aid the modelling of the sequential properties of the requirements, and (ii) ProB-based animation and visualisation tools to explore the system’s behaviour. Some of the safety properties involve dynamic behaviour which is difficult to verify in Event-B. For these properties we use co-simulation tools to validate against a continuous model of the physical behaviour