Safety Assurance for Autonomous and Collaborative Medical Cyber-Physical Systems

Medical Cyber Physical Systems of Systems (MCPSoS) refer to a set of systems that flexibly collaborate at runtime in order to render higher level functionality. Most systems in a MCPSoS offer a generic piece of functionality so that they can contribute to many totally different collaboration scenarios. Consequently, it is unknown at design time which systems will how collaborate at runtime. This unpredictability leads to new challenges for the assurance of safety, because established approaches always build on the assumption that systems and their environments are completely known. We believe that the safety research community has to pull together in order to tackle the challenge of unpredictability and that this requires an appropriate taxonomy in order to establish a common understanding of the challenge and related solutions. To this end, we propose enhancements based on a widely accepted taxonomy for dependable computing with respect to the system-of-systems aspect. Further, we will use the taxonomy to reflect on the new challenge of unpredictability and related solutions from the state-of-the-art, namely, safety contracts and dynamic risk assessment. Finally, we motivate an integration of the safety contracts and dynamic risk assessment and present some ideas on this integration. Throughout the paper, we use a real-world example to exemplify our proposed taxonomy and our thoughts.