How to test multiple domains in EVs
Understanding HIL testing
HIL is a well-established and understood test methodology used in-vehicle validation. The primary benefit of using simulation and models is to enable engineers to iterate their designs more rapidly. To completely validate a full vehicle design, HIL testing is required at a wide range of component levels.
For example, when examining a seat, subcomponent testing would be used to verify the ECU’s function as it interacts with different loads, see figure 1. System-level HIL testing might bring several motors together to test the operation of the seat as a whole. Multi-domain HIL testing is used to verify the function of the seat in combination with the infotainment system, which also can be used to control some of its function. Further down the line, the coordinated functions of adjustment, haptic feedback, heating, cooling, and infotainment input and display of the seat are tested to ensure safe and reliable operation. This is the purpose of the multi-domain HIL solution.
As vehicle systems are increasingly using complex electronic, intelligent, and interconnected systems to provide advanced safety and comfort features to vehicle occupants, performing system integration test using multi-domain HIL solutions is more critical than ever. This is because when systems come together, many unexpected behaviours can occur, which may be impossible to identify when testing in isolation, either at the component or sub-system level.
For example, multi-domain testing can reveal how the unexpected draw on a vehicle battery can compromise the performance of other electronics. Networking bottlenecks may also arise when multiple data-heavy systems like ADAS and powertrain are combined, resulting in a system slowdown. Even physical challenges can be revealed, such as grounding problems between ECUs that lead to unexpected values.
Finding such problems early in the design process, before even having a prototype vehicle for testing, can help engineers save valuable time, reduce costs, and avoid potential costly recalls for bugs otherwise not found by conventional testing. Realizing the significant competitive advantage multi-domain HIL solutions offer, organizations have begun deploying them, see figure 2.
However, being assured by the value of multi-domain HIL testing does not necessarily translate into a successful implementation. Because of the scale and complexity of these systems, proper configuration and set up can be a daunting task. Fortunately, several unique characteristics of tools from NI and its partners like Aliaro can help organizations successfully integrate multi-domain HIL testing in their validation process, see figure 3.
Open and Flexible Approach
Success in suing HIL testing relies on seamlessly integrating these toolchains, test cases, and models into one system. Applications can include test execution in Python along with a test system that comprises dSPACE and NI hardware, CANoe software, and ASAM XIL-related components integrated into one multi-domain HIL solution.
NI’s PXI modular hardware and open software make this integration possible, enabling designers to extend their current test capabilities with a wide range of modules to meet different system integration testing needs. VeriStand supports new and existing models in an HIL test system. Compliance with standards such as ASAM, AUTOSAR, and FMI further ensures additional suppliers’ offerings can be added in the future as requirements change.
Selecting a modular, open platform allows hardware and software to be reused as testing scales from component level to system level to full vehicle system testing. Aliaro specifically has enabled this by developing self-contained sub-system units that can be used in isolation to confirm the functioning of one ECU. These can also be incorporated into a system-level or multi-domain rack. Transitioning from system-level to multi-domain simulation is achieved by adding a master rack with a controller to integrate across multiple domains. Similarly, system definition files can be merged as new vehicle domains, and racks are introduced into the system, providing excellent flexibility and extensivity of the system for many years to come.
As figure 3 illustrates, these flexible, modular sub-system units interface with different ECUs (real, simulated, or via restbus) and their related software components to enable easy transition and reuse of components across sub-system- and system-level HIL testing. This ability to reuse simplifies the test setup and helps save engineering time and money.
Scalable and Reconfigurable
For full-vehicle testing, HIL systems need to scale to high channel counts with thousands of signal paths across multiple ECUs. Also, as designs constantly evolve, the ability to swiftly reconfigure these complex, multichannel systems can be the difference between efficient validation and endless frustration.
Aliaro Configurator software, shown in figure 4, provides a drag-and-drop interface to configure systems quickly. Adjusting to new requirements is simple and adding new ECUs by remapping signals takes few clicks of a button. It is also likely that based on design/prototype availability, developers would want to switch between real and simulated ECUs and loads. Because of this, the ability to activate and deactivate nodes or restbus simulations with streamlined ECU switching is another essential system capability.
Fully Automated Functional Test
Testing vehicle domains in combination with each other is increasingly important to validate an entire vehicle. As more and more systems work together, multi-domain HIL testing avoids unexpected behaviors materializing later on.
About the authors:
Selene Van Der Walt is Solutions Marketer, Body, Chassis, And Powertrain, NI
Mikael Bedemo, is CEO, Aliaro