In today’s highly competitive and cost-sensitive global automotive market, OEMs are transitioning to virtual validation processes to accelerate vehicle design, development, and testing. This leads to significant reductions in both development time and costs by enabling testing and identifying issues much earlier in the development cycle, even before hardware is available. One primary example of this virtual transition is the shift from software development and validation using physical ECUs and benches to using virtualized ECUs, also known as V-ECUs, and software-in-the-loop (SIL) simulation.
The Virtual Transition for Accelerated Vehicle Development
Since many OEMs have made the delivery of V-ECUs a program requirement to perform software verification at a system level, this is taken into consideration by Nexteer Automotive’s electric power steering (EPS) production programs. However, developing and integrating a V-ECU into a vehicle system while meeting quality and safety standards requires overcoming several challenges.
This is where Nexteer partnered with dSPACE to develop a Level 3 V-ECU using the dSPACE tool chain, particularly VEOS, to perform software verification with higher accuracy and reliability. Level 3 means that the V-ECU comprises the application software, the production basic software, and the drivers and operating system designed for the use in a virtual simulation environment. This way, the V-ECU provides behavior that is almost identical to that of the real ECU, allowing for comprehensive testing and validation where tests for the real ECU can be re-used in the virtual environment.
The growing complexity of software requires new approaches to testing. A seamless SIL and HIL simulation environment using V-ECUs and real ECUs increases efficiency by enabling effective, continuous validation during all development phases.
Functional Safety Standards for Development
As a leading global supplier of electric power steering (EPS), steer-by-wire (SbW), and other software-driven motion control solutions, Nexteer must meet Automotive Safety Integrity Level (ASIL) D classification. This is the most stringent risk level defined by the ISO 26262 functional safety standard for electrical and electronic systems. To comply with this industry standard, the most rigorous safety measures are required to ensure steering functionality and driver safety.
Given the rigor of ISO 26262, development and testing processes must be thorough and continuous, maintaining safety and quality throughout the entire product lifecycle. This includes everything from understanding customer requirements to evaluating edge cases and conducting final verification.
"With VEOS from dSPACE, we can accelerate innovation by validating functions early in the development cycle. The software-in-the-loop and V-ECU integration capabilities significantly reduce time-to-market and allow us to deliver high-quality vehicle software faster and more efficiently."
Simulation That Maintains or Enhances Safety & Quality
The success of this virtual transition goes beyond OEMs and depends on close collaboration across the entire supply chain. OEMs must rely on close collaboration with their suppliers to accurately and seamlessly integrate components into system-level simulation environments to ensure both precision and compatibility. This is especially true when it comes to simulating safety-critical components where strict adherence to automotive functional safety standards is crucial.
Developing a Level 3 V-ECU to perform software verification at a system level has many benefits for OEMs but meeting ASIL D functional safety presents several challenges that must be addressed:
Testing and Validation
Ensuring that the V-ECU behaves as expected across all potential driving scenarios, including edge cases, is a difficult task. A V-ECU is not a one-size-fits-all solution and must be continuously validated and tested under different conditions to ensure reliability and performance.
Model Portability
Integrating with tool chains can be challenging due to proprietary formats and differing abstraction levels. Ensuring model portability across simulation environments including model-in-the-loop (MIL), software-in-the-loop (SIL), and hardware-in-the-loop (HIL) without modification adds further complexity.
Nexteer’s Level 3 V-ECUs for Safety-Critical Components
By using V-ECUs, Nexteer aims to simulate interactions between multiple ECUs within the system, assess system behavior under different conditions, and identify potential issues before moving to physical hardware testing. This approach allows for comprehensive testing early in the development cycle, reduces the dependency on physical prototypes, and accelerates the validation process, while also ensuring robust software integration and performance.
By partnering with dSPACE, Nexteer developed a Level 3 V-ECU that enabled high-fidelity simulation of the entire electric power steering system while ensuring compliance with functional safety standards before deploying to physical hardware.
The dSPACE tool chain, particularly VEOS, enabled virtualized testing to help ensure the software would perform as expected and validate the EPS system behavior early in the development process.
The dSPACE VEOS tool chain played a critical role in overcoming many challenges, including the development of V-ECUs and restbus models: Nexteer used the dSPACE SystemDesk for software configuration and integration, as well as the creation of the Level 3 V-ECU. dSPACE Bus Manager is used for creating CAN restbus models and the Ethernet Package allows the creation of Ethernet restbus models.
Integration with Model-Based Development
VEOS seamlessly integrates with model-based development tools, particularly MATLAB/Simulink. This integration allowed developers to integrate the models from MATLAB directly into dSPACE products.
V-ECU Simulation
With the VEOS player, V-ECUs, environment models and restbus models can be integrated and connected to a simulation system, providing a high-fidelity V-ECU simulation enabling developers to test the ECU code as if it were integrated on the real hardware. The tool chain supports multiple communication protocols (CAN, LIN, Ethernet) while ensuring the virtual ECUs perform realistically, interact with other V-ECUs, and participate in bus communication of the entire vehicle networks.
Test Automation
dSPACE allows V-ECU testing through ControlDesk and AutomationDesk. This caters to manual and automated testing.
dSPACE tools offered smooth integration with MATLAB/Simulink, which Nexteer used for modeling and algorithm development. This seamless workflow between the modeling environment and the dSPACE testing platform helped us achieve a faster development process while minimizing errors during integration.
Development and Test Methods
The development and testing of the V-ECU involved several methods and best practices to ensure that the system behaves as expected in both virtual and real-world environments. These methods included:
Software-in-the-Loop (SIL): Early validation of control algorithms in a simulated environment.
Integration Testing: Ensuring the V-ECU works correctly at a system level once all the software content is integrated.
Fault Injection and Robustness Testing: Verifying the ECU's behavior under fault conditions and testing its fault tolerance.
Validation with Real-World Data: Correlating simulation results with real-world data to confirm the accuracy of the virtualized system.
The test created for the V-ECU covers a wide range of conditions and scenarios to ensure that the V-ECU behaves as expected in various environments. These test cases provide thorough validation of both individual functionality and overall system integration, ensuring the V-ECU is reliable, efficient, and capable of handling real-world conditions and edge cases.
Nexteer has had a longstanding relationship with dSPACE in hardware-in-the-loop systems. We are always impressed by their strong technical support and comprehensive training content. Considering their success in virtual ECU development and testing, customer feedback guided our decision to select dSPACE as our tool vendor for virtual ECU development and testing, using tools such as VEOS.
A Successful Collaboration
Together with dSPACE, Nexteer delivered a Level 3 V-ECU to its OEM customers which offered several key advantages:
Cost Savings: V-ECUs eliminate the need for OEMs to invest in additional hardware for testing and development. This also reduces the need for expensive test benches and other hardware-based testing tools during the early development cycle.
Faster Development Cycles: V-ECUs enable OEMs to start software testing even before the physical hardware is available. OEMs can use virtual ECUs to simulate various driving conditions and edge cases, thus speeding up the validation process.
Improved Validation and Testing: OEMs can detect potential issues in the software much earlier in the process, reducing the likelihood of costly mistakes in the later stages of development.
Seamless Integration: Virtual ECUs make it easier to integrate different components of a vehicle’s architecture without having to wait for the physical hardware to be ready. This is especially useful in the context of connected and autonomous vehicles.
In summary, dSPACE tools and their robust simulation and testing capabilities were crucial in supporting the development of a reliable V-ECU that fulfilled functional safety requirements and enabled Nexteer to meet their project goals and customer requirements. Using tools from a single vendor ensured model and simulation artifact transferability between simulation environments. Nexteer looks forward to continued collaboration with dSPACE to drive efficiencies in how they develop, test, and validate their safety-critical motion control solutions and better serve their global OEM customers.
