Shifting Vehicle System Development Left With Virtual ECUs

Developing electrical and electronic content for vehicles has always been an engineering and manufacturing challenge. The road is an exceptionally rough environment for components: temperature and humidity change constantly while noise and vibration pummel all parts of the vehicle. The nature of high-speed travel requires safety and reliability, which must be achieved in the presence of the difficult environmental factors. Further, there are many components within a vehicle that must interact on a continual basis, so robust intra-chassis communication is essential. With all these challenges, developers need to find design flaws and limitations as early as possible so that they can be corrected. It is far too late in the project to wait until prototype vehicles are on the road to perform thorough testing.

The traditional vehicular development process has relied mostly on bench testing, followed by road tests when prototypes are available. For much of the system, it is possible to design and replicate benchtop test setups. They are expensive to build, but they can be created earlier and at less cost than prototypes. Bench testing at one time represented a significant “shift left” in development, but it no longer suffices. Today’s vehicular electronic systems frequently contain custom chips that require months to fabricate, so finding design bugs on the bench causes major delays in the schedule. Further, some types of bugs are hard to find since they require injecting faults that can damage the bench setups. Developers need a more flexible approach providing a dramatic shift left.

The logical solution is virtual prototypes for vehicular electronic systems. Representing the systems in software and verifying in simulation is a powerful method that can occur before any chips are fabricated. Faults can be injected without adverse impact on the prototype, so the corrective responses mandated by the ISO 26262 safety standard can be verified. Virtual prototypes can be replicated quickly and inexpensively, making them available to more members of the development team. This is especially valuable for embedded software developers, who have historically required bench setups to test their code. According to Morgan Stanley Research, the software portion of a vehicle’s value will grow from 10% today to 60% in the near future. Virtual prototypes shift left the critical programming tasks with software in the loop (SiL) testing.

Perhaps no parts of vehicular electronic systems benefit more from this approach than the engine control units (ECUs). These components gather information from a multitude of in-chassis sensors, interpret the data, and adjust engine and vehicle performance by controlling a series of actuators. Traditional sensors include those that measure air flow, air temperature, coolant temperature, manifold pressure, throttle position and vehicle speed, and traditional actuators control the engine’s air–fuel mixture, ignition timing, idle speed and other parameters. Advanced driver assistance systems (ADAS) and autonomous vehicles have greatly increased the role of ECUs, which now gather sensor data from cameras, radar and lidar, and may control every aspect of the vehicle’s operation, including acceleration, braking, and steering.

Modern ECUs are based on microprocessors and have significant software content. Therefore, virtual ECUs are key parts of any virtual prototype for modeling and testing both the hardware and embedded software for vehicle electronic systems. As a provider of solutions for development of automobiles and other vehicles, Synopsys supports virtual ECUs and virtual prototyping from system to software with a set of advanced products. These include Synopsys Silver, a virtual ECU platform that moves development from bench rigs to a personal computer (PC) for fast and efficient iterative development of ECU software.

With Silver, engineers can build virtual ECUs that serve as software execution models of the physical units. Different parts of the ECU software such as application software (ASW) and basic software (BSW) layers can be virtualized and simulated. The Synopsys solution provides extensive connectivity and test integration with all parts of the automotive tooling ecosystem. Silver runs SIL simulations to develop ECU software and test the interaction among vehicle components. When these simulations entail running production code, Virtualizer executes the actual binaries that will run in the vehicle. This provide highly accurate simulations of system behavior and prevents surprises when the software is run in the physical prototypes. Silver also runs system-level tests to achieve a high level of coverage.

Traditionally, most virtual prototypes for vehicular electronics have run on Windows PCs. One important aspect of the Synopsys solution is that it supports Linux as well as Windows. This allows developers to write code, build virtual ECUs, run tests and debug all on a Linux workstation. There is no need to switch back and forth between Windows and Linux environments, enabling tight interactive simulation loops with short turnaround times. The Synopsys approach also support continuous integration (CI) and test of the virtual ECU. Every time that the programmers commit new or changed software, this triggers an automatic update of the Silver model from a Linux workstation to Linux server infrastructure in the cloud, where the build and test process occurs. Both short-running tests to verify the software and exhaustive overnight runs with long-running tests are supported.

Virtual ECUs shift left the development process with earlier testing and faster feedback loops, they are scalable and less expensive across project teams, and they make debugging easier. Operating in an SiL virtual prototyping environment, they enable safer vehicles by testing faults that would be hard to introduce in bench setups or prototypes. Virtual ECUs are an essential part of developing complex vehicular electronic systems. A white paper is available with more technical details on how the design and test flow works. There is also the upcoming “Virtual Prototyping Day – Silver: Accelerate Your Innovation with Virtual ECUs” on Wednesday, November 10, 2021. Industry leaders from Synopsys, Daimler, and Hyundai Transys will share the latest innovations, methodologies and experiences using Synopsys Silver virtual ECUs. More information and registration details are available here.