Design Safe Software via UML-based SFTA in Cyber Physical Systems
In cyber physical systems (CPSs), hazards can lead to injuries, deaths, destructions or loss of vital equipment or environmental damages. In these systems, software controls the behavior of mechanical and electronic components as well as their interactions; therefore, it plays a special role in creating system hazards and its safety plays a crucial role in a risk management process in cyber-physical systems. Many methods can be used to establish safety in software components of these systems and the software fault tree analysis (SFTA) is among the main methods. The main purpose of SFTA is to identify possible deficiencies in software requirements, design or implementation, which may result in undesirable events in software. On the other hand, unified modeling language (UML) is among the methods used for assurance the construction of object-oriented software. In this paper, a sequence diagram generated in the software production process and the SFTA are used to evaluate safety. The proposed method can play a major role in designing safe systems. The proposed method for designing safe software is implemented in a real CPS and due to the use of uncertain data the reliability of the system is calculated using SFTA-based Fuzzy.