Modeling and Analysis of Safety in Early Design

In this paper we present a method of explicit inclusion of safety into a model-based design method for cyberphysical systems. This approach enables an analysis where component-level failures can be mapped to potential system-level hazards. Application of this work presents several significant advances to the fields of safety engineering and design. This paper present a method of representing the safety property of a system by the introduction of the concept called the “safety function.” Further, the function of achieving safety is mapped to the performance functions of the system. We present a process of concurrently developing a system concept from the safety and functional perspective. The end result of this process is a system architecture where components of the system are explicitly mapped to both the functions they perform and the role it plays in ensuring safe system operation. The benefit of this approach is having a system representation that allows for analysis of critical events and off- nominal component behavior to identify potential losses in function and safety constraint violations. The approach is demonstrated on a software controlled hardware system. Namely, a generic spacecraft reaction control system