Component-based design of cyber-physical applications with safety-critical requirements

Cyber-physical systems typically involve large numbers of mobile autonomous devices that closely interact with each other and their environment. Standard design and development techniques often fail to effectively manage the complexity and dynamics of such systems. As a result, there is a strong need for new programing models and abstractions. Towards this, component-based design methods are a promising solution. However, existing such approaches either do not accurately model transitory interactions between components – which are typical of cyber-physical systems – or do not provide guarantees for real-time behavior which is essential in safety-critical applications. To overcome this problem, we present a component-based design technique based on DEECo (Dependable Emergent Ensembles of Components). The DEECo framework allows modeling large-scale dynamic systems by a set of interacting components and, in contrast to approaches from the literature, it provides mechanisms to describe transitory interactions between them. To allow reasoning about timing behavior at the component-description level, we characterize DEECo’s closed-loop delay in the worst case, i.e., the maximum time needed to react to a change in the environment. Based on this, we incorporate real-time analysis into DEECo’s design flow. This further allows us to analyze the system’s robustness under unreliable communication and to design decentralized safety-preserving mechanisms. To illustrate the simplicity and usefulness of our approach, we present a case study consisting of an intelligent crossroad system.