Unreal Engine - FMI Plugin (UEFMI)

Background

• The UEFMI plugin allows for the use of dynamic simulation models via Functional Mockup Units (FMUs) directly in an Unreal Engine project.
• An FMU is code that has been packaged according to the Functional Mockup Interface, a free and open-source standard for exchanging dynamic (i.e., time-dependent) simulation models.
• Common examples of models that get packaged into FMUs are:
  • Physics based vehicle simulators (e.g., drive train, HVAC, water vehicles, etc.)
  • Energy systems (e.g., power plants, buildings)
  • Space systems (e.g., solar sail mechanics, propulsion systems)
  • And many many more...

Prerequisites

This work was tested using the following. It may work on something else but no guarantees.

• Windows 10
• Unreal Engine 5.3+
• Visual Studio 2022
• An unzip utility on path, currently supported are unzip, 7z, tar

A_FMU -> The Workhorse

A_FMU under UEFMI C++ Classes/UEFMI/Public contains the magic to make the FMU run. Users are highly encouraged to look at A_FMU.cpp if they need to understand more intimately the implementation. A couple important notes are:

• PathFMU is the location of the FMU and supports relative or absolute paths.
• mResults returns the results requested from the variables added to mStoredVariables.
  • mResults only returns values when mAutoSimulateTick = True. Else it is empty and variables must be be retrieved using the GetReal() function.
• mModelVariables are the names of all availble variables found in the model which could be added to mStoredVariables.

Installation

As a plugin, UEFMI is intended to be used inside an existing Unreal Engine project!

The process below will go through the steps to adding the plugin to a new Unreal Engine project.

1. Create an Unreal Engine project. Fror illustration purposes let's call it MYPROJECT.

   • Go to the project MYPROJECT folder and create a Plugins folder if it doesn't exist.

     cd MYPROJECT
     mkdir Plugins

2. Clone the repository and submodules. To do that, in the `MYPROJECT/Plugins folder:

   cd Plugins
   git clone https://github.com/ORNL-Modelica/UnrealEngine-FMIPlugin.git UEFMI
   cd UEFMI
   git submodule init
   git submodule update

   • Note:
     • git submodule update --remote to grab the latest commits instead of specific commit

3. Copy the files from the submodule to the UEFMI plugin source folder (choose one option). In MYPROJECT/Plugins/UEFMI folder:

   • Auto:
     • Run setup.bat (Windows) or setup.sh (Linux)
   • Manual:
     • Copy files:
       FMU.cpp, FMU1.cpp, FMU2.cpp
     • From:
       ThirdParty/fmikit/src
     • To:
       Source/UEFMI/ThirdParty/fmikit/src

4. Run the Unreal Engine project

   • Double click MYPROJECT.uproject and rebuild the plugin if prompted.
   • Or right-click MYPROJECT.uproject and select Generate Visual Studio project files and then open MYPROJECT.sln

Test Installation

These examples use the test.fmu included in the repo. The FMU provided will be extracted to a temporary folder called fmus at the top level of the UE project folder.

test.fmu is a Lorenz System model model created from the Modelica source code test.mo

• Level_0
  • This level provides example blueprints (BP_FMU) demonstrating the automatic and manual options for simulating an FMU.
  • BP_FMU implements the A_FMU class.
• Level_1
  • Simple use of A_FMU and printing a variable to the screen via the level blueprint.

Known Issues

• Currently only floats and booleans (i.e., 0/1) are supported variables in A_FMU.
• Has not yet been tested on non-Windows OS.

License

Copyright 2019 UT-Battelle. The code is released under the Apache License, Version 2.0.