CPSSim: Simulation framework for large-scale Cyber-Physical Systems

Thanks to the active development on embedded, real-time, and control systems in last thirty years, we are now in the era of integrating these well-studied/designed systems as a large scale and complex systems, called Cyber-Physical Systems, to provide context-aware and user-centric services. In the processing of developing CPS, one of the major challenges is how to integrate the technologies developed by different communities into a coherent system. This paper presents the design and implementation of CPSsim, which is a framework to integrate several simulators, each of which simulates either discrete or continuous systems, to simulate the federated system. CPSsim enables the developers to use the simulators designated for the sub-systems of a CPS and to understand the behavior of the integrated system. Hence, there is no need to build a new simulator from scratch. In order to simulate the cyber-physical systems, the framework concurrently simulates the sub-systems working at different rates, and tackles the scalability issue. Furthermore, CPSsim targets the synchronization issue among simulators, each of which may adopt different simulation models and has different timing properties. To demonstrate the effectiveness, we use active train control as an example CPS and evaluate its performance.