FMI for PC-Based Simulation

Use Case: Integrating Functional Mock-up Units

This use case example demonstrates how Functional Mock-up Units (FMUs) from different vendors can be integrated to form one simulation application for PC-based simulation with dSPACE VEOS.

The Use Case

The demo is based on an existing HIL project and demonstrates the frontloading of HIL tests and the simulation of FMUs. dSPACE VEOS is used as a PC-based simulation platform. The dSPACE tools ControlDesk and MotionDesk are used to control and visualize the simulation. The demo system consists of a vehicle environment model with different model parts and an ECU model for the electronic stability program (ESP). For the vehicle dynamics model, parts of dSPACE’s Automotive Simulation Models (ASM) are used. The original ASM engine and drivetrain model parts are replaced by real-time-capable C code FMUs. Dassault Systèmes provided the engine model, developed in Dymola, and ITI provided the drivetrain model, developed in SimulationX. Both were developed according to a physical modeling (acausal) approach. The FMUs are based on the Functional Mock-up Interface (FMI 2.0 RC1) for Co-Simulation.

The FMUs, the ASM model parts, and the ECU model are integrated in VEOS to form an overall system model.

The Workflow

The screenshot shows an interface representation of the drivetrain FMU, provided by ITI, within the Simulink model. The in- and outports represent the FMU interface and are used to connect the FMU to the Simulink model. Similar interfaces exist for the other FMU and the ESP ECU model.

All model parts are imported into VEOS Player, the integration tool for the VEOS platform. VEOS Player connects the FMU interfaces with the in- and outports of the other models, integrating them to an overall model of the system. This overall model is then ready to be downloaded and simulated with VEOS.

ControlDesk is used to start and control the simulation. Its photorealistic experiment layouts give a detailed impression of the car dashboard. All model variables and parameters, such as yaw rate, brake pressure and velocity, are displayed and plotted during the simulation run to constantly give you up-to-date information about what is being simulated.

This demo system tests the functionalities of an ESP ECU model. The same simulation scenario – a car braking on a slippery road – is performed twice, once with ESP turned off and once with ESP turned on, each in a separate simulation run.

MotionDesk visualizes the simulation run so the vehicle behavior is shown graphically in both simulation scenarios, i.e., with the ESP ECU functionality turned off or on. In the first simulation run, with the ESP ECU functionality turned off, the car starts to skid and spin during braking. With the ESP ECU functionality turned on, the braking maneuver brings the car to a controlled stop. Because the test drive is recorded, you can play both runs simultaneously to compare their behaviors directly on screen.