Moving from Domains to Zones: The Auto Architecture Revolution

What you’ll learn:

  • The shift from conventional electrical and electronic (E / E) architecture to the vehicle and domain and zonal architectures.
  • How software is taking over hardware and defining the vehicle and its key components.
  • How automotive manufacturers are now moving from domain to zonal architectures.
  • Challenges with — and a solution to — the zonal approach implementation.

The wiring harness in many vehicles is now more than any other component, except the engine — whether it’s an internal combustion engine (ICE) or a battery-powered electric motor. Reducing this unsustainable burden demands an entirely new approach to interconnection architectures, and it can be realized using high-speed serial buses and networking technologies alone.

To fully address the issue of a fundamental shift in how hardware and software functions are partitioned across newly configurable platforms.

Dividing into Domains — and the Need for a Zonal Approach

Due to the increasing complexity of conventional vehicle architecture, the addition of more and more electronic control units (ECUs), an alternative approach to additive structure and hierarchy. The approach was to divide the vehicle into “domains,” or areas with common functionality — such as the chassis, powertrain, body & comfort and infotainment, and ADAS — and connect them to a centrally located service-oriented gateway via a dedicated domain controller. (Fig. 1).

However, the downside to this approach is that many (if not all) of the domains physically span the entire vehicle. Therefore, instead of organizing the domains by a function, a zonal approach organizes the location where all of the functions — lighting, suspension, indicators, image sensors, and braking — are controlled by the zonal controller. (Fig. 2). However, this approach requires modularity and flexibility.

Modularity means that there are high degree of commonality between system elements, such as ECUs, that have the same hardware as different functions. These devices will be defined by the software that is embedded within them.

Flexibility refers to the ability of the vehicle to be tweaked and reconfigured over time. Combining software-defined ECUs with the ability to deliver over-the-air (OTA) updates to the firmware provides this flexibility and allows automakers to easily support the vehicles. This can include addressing software defects (“bugs”) as well as adding new features or enhancing existing ones.

Zonal-Approach Implementation in Challenges

While the automotive industry has relied on CAN networking for many years, it’s becoming increasingly apparent that the demand for vehicles today. This is especially the case for the “backbones” that connect to the zonal gateways, which will be based on Ethernet. However, the hierarchical nature of the zones will introduce more “hops” into the network, causing latency and jitter issues.

Many of the systems have a modern vehicle with time dependencies, which are particularly critical in safety-related systems, such as ADAS. While opening a window or changing a radio station would be an inconvenience, a delay to a message from a camera that has detected an obstruction resulting in brakes being too late to be catastrophic.

These highlights a weakness of traditional Ethernet in that data packets are only propagated when the backbone is free of other traffic, and there is no hierarchy of relative importance. Simply put, traditional Ethernet would look for a data packet that would be equally as important as a radio station.

In-vehicle networking will be based on IEEE 802.1AS-2020, the IEEE-approved standard for timing and synchronization in time-sensitive networking (TSN) applications. Often called “deterministic Ethernet,” this standard includes several features for ensuring that data is managed on a strict time basis, including ensuring that time-sensitive traffic is the shortest path.

This high-speed Ethernet will form the backbone of the zonal architecture and connect zone controllers with one another as well as central computing resources. However, as things become more complex, there are multiple types of edge networks to be found, connecting the zone controller to various edge ECUs. While Ethernet may be used in some cases, a significant amount of CAN infrastructure may exist in both CAN (FD) and CAN XL formats.

Several areas should be considered for this multi-protocol approach. In particular, the designer must consider how data is moved and the Ethernet backbone to and from the in-zone network. This is further complicated by the fact that CAN traffic is mostly periodic and broadcast, compared to Ethernet, which is usually event-based and point-to-point.

As in-vehicle networking (IVN) becomes more important and powerful, the complexity will rise, with multiple elements incorporating networks, including switches and gateways. While this complexity is necessary to build a resilient network, some simplification must be achieved so that the components (and therefore the entire network) are configured.

Software-defined networking (SDN) can be used to simplify how network components are configured by the interface so that the configuration is hardware- and vendor-agnostic. Because this can also be achieved by OTA, optimized network configuration may become part of the manufacturer’s updates as well as if needed at a fleet level.

Functionality moves from domain controllers to zonal controllers and the central processor to a zonal architecture. Thus, applications are mapped over multiple processing and network hardware, with individual data sharing multiple data streams and functions. The increased workload can be a source of latencies and jitter that are highly undesirable in time-sensitive applications.

As a result, hardware performance and throughput are key considerations when planning a zonal architecture. Often the central controller will incorporate sophisticated task-scheduling algorithms to minimize multicore processors’ delays, while the network will be based on high-performance technologies such as time-sensitive Ethernet.

The final concern is safety and security, which in turn increases the importance of vehicles becoming more connected and more autonomous. This multi-faceted area is concerned with functional safety that detects and addresses critical components, and ensures that failure-safe operation as well as overall zonal architecture is vulnerable to malicious external attacks.

The Zonal Solution

A zonal architecture could cover almost all of the infinite number of ways the key functions of connectivity, network control, real-time I / O, and application / service management. Within NXP’s proposed solution, there are three categories of zonal gateway: the zonal aggregator, the zonal controller, and the zonal processor (Fig. 3).

The zonal aggregator Has the sole role of traffic management, aggregating different data types with varying criticality, safety, and security requirements. But the “execution” of the data execution pipeline requires both “understanding-think-act”: accessing and exiting the data highway, and, finally, the reconversion of Ethernet packets into CAN or LIN bus signals without the impact of criticality. , every bit of information on safety or security requirements.

In addition to traffic management, the zonal controller adds real-time processing and takes care of advanced network processing. Here, the sensors, actuators, and, to some extent, functions, are locally connected to zonal controllers. These can also be considered mini gateways because this is where a CAN or LIN meets Ethernet. The zonal controllers are then connected through a high-speed Ethernet network backbone to the center, the brain, of the car.

Finally, the zonal processor The same features are involved in the network, but it adds application capability and advanced gateway services.

On this front, NXP offers integrated solutions designed to implement an Ethernet TSN switch (SJA1112 / 1110) and multicore processors from the S32 platform that can scale across three zonal-gateway categories (zonal aggregator, zonal controller, and zonal processor) well-functionally safe power-management devices.

Summary

The automotive industry is one of the underlying unprecedented change with technology-laden vehicles that enable connected, electrified self-driving. To fully implement this, many future ECUs and sensing devices will be added to almost every car, requiring a basic rethink of the vehicle architecture — not least, the size and weight of the wiring harness.

While early initiatives have incorporated domains into the vehicle, the zonal approach is more likely to be the preferred approach, as is its capacity, flexibility, and ability to constrain costs.

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