FMI for Co-Simulation of Embedded Control Software

Increased complexity of cyber-physical systems within the maritime industry demands closer cooperation between engineering disciplines. The functional mockup interface (FMI) is an initiative aiding cross-discipline interaction by providing, a widely accepted, standard for model exchange and co-simulation. The standard is supported by a number of modelling tools. However, to implement it on an existing platform requires adaptation. This paper investigates how to adapt the software of an embedded control system to comply with the FMI for co-simulation standard. In particular, we suggest a way of advancing the clock of a real time operating system (RTOS), by overwriting the idle thread and waiting for a signal to start execution until return to idle. This approach ensures a deterministic and temporal execution of the simulation across multiple nodes. As proof of concept, a co-simulation is conducted, showing that the control system of an SCR (selective catalyst reduction) emission reduction system can be packed in a functional mockup unit (FMU) and co-simulated with a physical model, built in Ptolemy II. Results show that FMI can be used for co-simulation of an embedded SCR control software and for control software development. Keywords: Co-Simulation, RTOS, FMI, FMU, Embedded Systems