FMI for Co-Simulation of Embedded Control Software

Increased complexity of cyber-physical systems within the maritime industry demands closer cooperation be-tween engineering disciplines. The functional mockup interface (FMI) is an initiative aiding cross-discipline in-teraction by providing, a widely accepted, standard for model exchange and co-simulation. The standard is sup-ported by a number of modelling tools. However, to im-plement 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 ap-proach 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 soft-ware and for control software development.