Zonal Architectures Unlock Future Automotive EE Design
October 27, 2023
The electrical/electronics (EE) architecture of mass market automobiles is evolving rapidly to meet requirements for seamless connectivity, upgradable software, network and vehicle wide security, and management of increasing complexity, all while reducing design cycle time and offsetting higher computing costs by easing system integration. It’s a big task list, and the key to success is movement from traditional distributed control networks to a zonal architecture based on Central Computer Systems.
Typical production vehicles today may contain 60 to 100 electronic control units (ECUs) that manage the operation of specific vehicle domains, for example, powertrain, chassis control, and auxiliary systems.
Each ECU in turn contains a microcontroller (MCU) computing core and system memory with many I/O connections to various sensors and controls. As features have been added over the years, this architecture has become extremely complex and inflexible. Drawbacks include difficulty in updating the software since the ECU has no direct connection to the outside world and a plethora of interdependencies that make it difficult to implement changes that comply with rigorous safety and quality requirements. For example, separate domains often are designed for compliance with varying functional safety specifications (ASIL-A, B, etc.) and maintaining the proven reliability of each ECU is a critical element in any architecture transition.
Entering the Automotive Zone
An increasing number of vehicle designs in the second half of this decade will begin to replace this domain-oriented approach with more powerful computing systems organized in a zonal architecture. With the large number of legacy systems that exist, the change is taking place in intermediate steps, with the result being a significant reduction in the number of control units, greater flexibility of each vehicle platform, and the ability to implement remote updates of vehicle systems.
One approach to the transition is based on using two or more Central Computer Systems (CCS) that each incorporate several zone controllers to aggregate functions handled by separate ECUs. In a typical scenario, the CCS units would be centrally located in the vehicle and Zone Control Units (ZCUs) would be dedicated to managing all electronics in different sections of the vehicle.
In this geographic arrangement, each zone controller supports all hardware and associated software located in the physical area (i.e., frontal, right, left, and rear zone). The CCS units address high-level control functions; for example, cockpit domain control and networking, and coordinate all the zone controller activity related to these functions.
The ZCUs in turn interface with power distribution systems, vehicle sensors, and actuator units related to the specific functions. Middleware in the ZCU is designed to be updatable via secure network interfaces, which enables the flexibility of software defined vehicle features made available by the vehicle OEM.
Toward the latter half of this decade, a variant layered approach may be implemented by some OEMs. In this architecture, a top-level, high performance central computing layer has several modules, for instance, one doing real time control, and another for Adaptive AUTOSAR (AA) or POSIX-based applications.
The next layer has as many as 5-10 zones that are ASIL-D (highest functional safety) capable. This would include power distribution, chassis, body, and safety ECUs. The lowest final layer consists of such intelligent edge devices as smart sensors and small ECUs, as well as miscellaneous legacy hardware.
The Integration Roadmap
Vehicle OEMs are taking varied routes to the zonal future, with some choosing to initially integrate body systems and planning staged transitions into powertrain and safety zones, combined zones, or even vehicle motion, chassis, and propulsion in a single zone.
Regardless of the specific strategy, the common theme of building a Central Computer System that is responsible for a group of ZCUs and related legacy systems is consistent. This creates opportunities for innovation, particularly in functions that benefit from smart control and upgradeability, while legacy systems such as a fuel pump remain relatively unchanged.
Dealing with architectural variations that occur when implementing zonal architectures is a familiar challenge for Infineon, which supports this aspect of the automotive revolution both with new products and an understanding of the systems level issues that need to be addressed. More information about our Zonal Architecture solutions is available on our website.