How to Analyze the Safety of Concepts for a System-of-Systems?

Developing safety-critical products like cars, trains, or airplanes requires rigor in following development processes, and evidence for product safety must be collected. Safety needs to be considered during each development step and traced through the development life cycle. The current standards and approaches focus on single human-operated products. The technical evolution enables integrating existing products and new autonomous products into system-of-systems to automate workflows and production streams. Developing safety-critical systems-of-systems requires similar processes and mapping to safety-related activities. However, it is unclear how to consider safety during different development steps for a safety-critical system-of-systems. The existing hazard analysis methods are not explicitly mapped to developing a system-of-systems and are vague about the required information on the intended behavior. This paper focuses on the concept phase for developing a system-of-systems, where different technical concepts for a specific product feature are evaluated. Specifically, we concentrate on the evaluation of the safety properties of each concept. We present a process to support the concept phase and apply a model-driven approach to capture the system-of-systems' relevant information. We then show how this knowledge is used for conducting an FMEA and HAZOP analysis. Lastly, the results from the analysis are mapped back into the sequence diagrams. This information is made available during the next development stages. We apply the method during the concept phase for designing an industrial system-of-systems. Our approach helps to design complex system-of-systems and supports concept evaluation considering the criticality of the concept under consideration.