The early and virtual validation of electronic control unit (ECU) functions is becoming increasingly important for the development of modern vehicles in the automotive, off-highway, and aerospace industries. Virtual prototypes of ECUs, also known as virtual ECUs or V-ECUs, are indispensable for this, but their interchangeability beyond the limits of individual manufacturers and tools poses a challenge. This is where the Functional Mock-up interface (FMI) standard comes into play. The standard is not new, but it is under constant development – one current focus is on network communication; refer to our previous blog article.
In this article, you will learn how you can best evaluate the FMI Layered Standard for Network Communication for yourself and prepare for its use at an early stage. Find out how the standard helps OEMs and suppliers efficiently create and use V-ECUs. This article highlights the core problems that OEMs and suppliers face in virtual validation and how the standard can solve these in the future.
What challenges do OEMs and suppliers face when exchanging V-ECUs?
The exchange of V-ECUs between OEMs and suppliers poses different challenges for both sides.
OEMs want to put the ECU functionality into operation in an overall system or subsystem at an early stage and are therefore dependent on the timely delivery of V-ECUs by their suppliers. They must specify the precise form in which they want to receive the delivery. Manual effort is often required in order to integrate the supplied artifacts into the simulation environment. If the implementation does not precisely meet the requirements, additional iterations between the OEM and the supplier are necessary.
Suppliers have their own development process for the ECU software. Before they can supply a V-ECU to the OEM, it must have already been thoroughly tested and put into operation – normally before the first hardware prototypes are available. In addition to virtualizing and validating the ECU software, they must then invest significant effort to precisely adapt the V-ECU to the OEM's specifications and requirements.
The current workflows therefore require additional effort for adapting the interfaces, the manual integration of the V-ECUs into the simulation environments, and frequent iterations between the OEM and the supplier. This clearly demonstrates how important a standard is for the efficient exchange of V-ECUs.
How does the standard help OEMs and suppliers overcome the challenges?
A standard for V-ECUs in the field of network communication is therefore crucial for meeting the challenges described above. The layered standard offers several benefits for this:
- High interoperability and cost reduction: OEMs and suppliers often use in-house solutions or rely on tool chains from different manufacturers. FMI has established itself as the standard for the integration of environment models and is therefore supported by numerous simulation platforms. Since the FMI Layered Standard for Network Communication is based on the principles of FMI 3.0, existing simulators that support the FMI 3.0 core standard can be used without additional extensions, even for the simulation of V-ECUs with a bus connection. This reduces the implementation costs and ensures high interoperability. At the ASAM International Conference 2024, the FMI working group impressively showed how smoothly the exchange of V-ECUs and the interoperability of various tools work in practice thanks to the layered standard.
- Versatile applicability for the widest variety of use cases: The simulation scenarios of OEMs and suppliers often differ. OEMs often build simulation systems with several V-ECUs in order to validate the interaction of the supplied ECUs. Suppliers, on the other hand, tend to perform isolated testing and use restbus models, for example. The layered standard supports both: OEMs can realize complex simulation scenarios including the simulation of network errors, while suppliers can connect a V-ECU directly to a restbus model. The standard ensures that the V-ECUs can be used in both scenarios without adjustments. In addition, it takes the different development phases of a V-ECU into account. In early phases (Level 1), network messages can be transmitted based on signals, while a simulation at the level of bus drivers is possible in advanced phases (Levels 2-4).
- High consistency and quality as well as rapid expandability: The layered standard is developed within the FMI project of the Swedish non-profit organization Modelica Association, ensuring both independence and the necessary consistency. The quality of the standard is ensured before its release through the exchange of V-ECUs in the context of cross-checks. In addition, the openness to contributions to the standard enables innovations and new bus types to be promptly integrated into the standard.
- Simplified specification and implementation: OEMs no longer have to explain to their suppliers in detail what is to be supplied for the validation. The new standard provides specifications, demos, guidelines, and sample code. Suppliers do not lose valuable time but immediately know how they must implement the requirements without needing additional explanations.
How is the standard supported in the dSPACE tools?
The FMI layered standard has the potential to fundamentally change the collaboration between OEMs and suppliers in the validation of their ECUs. At dSPACE, we are committed to supporting its introduction and establishment to the best of our ability. Its implementation into the dSPACE tools therefore plays a central role for us.
CAN support: With dSPACE Release 2024-B, the layered standard for CAN is supported by the following dSPACE tools:
- SystemDesk, our tool for the generation of V-ECUs
- VEOS, our platform for PC-based simulation
SystemDesk users can therefore now create V-ECUs based on the new layered standard. They can then easily import these standardized V-ECUs into VEOS. There, the V-ECUs can be connected to restbus simulations in the form of bus simulation containers (BSCs), for example.
FlexRay support: In addition, a preview version with FlexRay support is available. This enables users to already take the first steps in the creation and simulation of V-ECUs with SystemDesk and VEOS at an early stage.
Existing users of our tools can continue to use them as usual and also enjoy these new, additional features:
SystemDesk
MCAL modules for the CAN and FlexRay bus drivers can now also be integrated into V-ECUs that are subsequently to be exported as FMUs (*.fmu). This means that V-ECUs can be created on the basis of FMI 3.0 and the Network Abstraction of the layered standard.
VEOS
The simulation platform now automatically recognizes Functional Mock-up Units (FMUs) with FMI Layered Standard for Network Communication based on Network Abstraction during import and creates corresponding bus controllers for them. Restbus simulations in the form of BSCs for CAN can still be connected directly to V-ECUs. Thanks to the bus simulation integrated in VEOS, the creation of complex simulation systems is considerably simplified. Bus controllers can still be connected via drag & drop, and the bus behavior is simulated in detail as usual.
Summary and Outlook
At the ASAM International Conference 2024, the FMI layered standard was presented to a wider audience for the first time. The FMI working group impressively demonstrated how smoothly the exchange of V-ECUs and the interoperability of various tools work in practice thanks to the new standard.
At the end of 2024, the layered standard for CAN reached the important milestone of "Release Candidate" – the official 1.0.0 release is imminent. At the same time, the specifications for FlexRay and Ethernet are progressing rapidly, and LIN is also already on the roadmap. As all bus types are based on the same fundamental principles, further milestones can be expected soon.
Due to the high degree of maturity of the "alpha" and "beta" versions of the layered standard, we at dSPACE have decided to already support them in SystemDesk and VEOS. CAN support has already been implemented, full support for FlexRay will follow shortly, and Ethernet support is also being worked on intensively.
The great interest and the consistently positive feedback from our customers motivate us to continue our involvement in the FMI committee and to further advance the support provided by our tools. We are excited about the possibilities offered by the FMI layered standard and look forward to shaping the future of virtual validation together with our customers.
About the Authors
Markus Süvern
Team Lead, Production Software & SIL Simulation, dSPACE GmbH
Christian Becker
Product Manager, Production Software & SIL Simulation, dSPACE GmbH
