Clock Synchronization in Context of the Distributed Co-Simulation Protocol

Today co-simulation methodologies are widely used for automotive system development. This approach supports distributed development and test of subsystems, which are engineered by different suppliers. The Functional Mock-Up Interface (FMI) as an open standard enables seamless integration of simulation models, tools and solvers. The recently published Distributed Co-Simulation Protocol (DCP) is an open standard application layer communication protocol. It represents a solution for the integration of models or real-time systems into simulation environments. While the DCP was designed for low overhead and realtime capable operation, it does not specify the exchange of time information during simulation. The DCP currently relies on external mechanisms for time synchronization. In this paper, we propose an extension to the DCP, enabling time synchronization between DCP slaves and the master. This enables time triggered exchange of simulation data, applicable to the DCP's real-time and non-real-time operating modes. Therefore it becomes possible to synchronize time between participants of a distributed co-simulation scenario. Many applications may benefit from our approach, including hardware- or software-in-the-loop scenarios, or mixed real-virtual prototypes for e.g. automated driving. We demonstrate the functionality of our extension with a use case from the automotive domain, which implements a lane keeping assist system.