Wouldn’t you love to read a book while driving?
Personally, I enjoy driving my own vehicle, and I am unsure of how comfortable I would feel about the process being fully automated. I like the idea of being able to take control over my vehicle when I need to, but it would be nice to be able to recline in the back seat on a long road trip. The automotive industry hasn’t brought self-driving cars to this level just yet, but rest assured, this is envisioned to be a reality in the not-too-distant future.
When looking at the regulatory and industry landscape around driverless vehicles, there are plenty of issues to consider that relate to safety and reliability of these systems. For the electronics industry and PCB designers, the standards landscape is still unclear, and designing to industry standards is bound to be an important consideration in such a highly regulated industry. Let’s take a look at the current standards landscape for PCB designers that are working on systems for connecting and controlling autonomous vehicles.
The Standards Landscape for Self-Driving Cars
IHS Market estimates that there will be 78 million semi-driverless or driverless cars on the road by 2035. Level 4 automated vehicles, which are defined as being fully automated and do not require a driver’s attention by the SAE, are already on the road, although not commercially available. Level 2 automated vehicles can already be purchased from major car companies, but the first Level 3 vehicle is still facing a legal quagmire in the U.S.
The issue regarding standards is not one of functionality. Rather, it is one of reliability. Self-driving cars require levels of redundancy and fail-safe measures in order to ensure the safety of passengers. If a PCB for a certain critical control or safety system in a self-driving car were to fail, the vehicle needs to have some level of redundancy that, at minimum, allows the vehicle to bring itself safely to a stop. These systems may also require that the driver take control over the vehicle in order to prevent an accident.
The regulatory landscape is confusing enough and already varies widely. Aside from the confusing regulatory landscape surrounding self-driving cars, the industry still has yet to come together on consistent standards that will govern the mass of new electronics that enable all the tasks required for safe self-driving cars. One can already expect that newer standards on vehicles will go beyond the existing IATF, IPC, ISO, AEC, and SAE standards on safety and functionality.
In addition to the standards organization listed above, the Automotive Electronics Council (AEC) defines testing requirements for automotive-grade components and systems. The ISO-26262 standard already covers functional aspects of design, integration, and configuration for automotive systems. The ISO 26262 standard was developed in 2011, and newer cars contain much more software than they had back in 2011. ISO 26262 Part II was recently released, and the ISO/WD PAS 21448 standard for ADAS systems was recently the subject of discussion at the SAFECOMP 2019 conference. We can already see new certifications for functional safety of electrical/electronic systems emerging from numerous organizations. These standards, as well as other ISO standards on the manufacture of PCBs, should be taken as a baseline for current designers of electronics for autonomous vehicles.
For software developers, an ASPICE certification will also continue to be relevant, even as the number of autonomous cars hitting the road increases. ASPICE defines "what the software should look like", rather than "how the software should be developed." Although the software for self-driving cars is complex, the software development process is unlikely to significantly change. I would expect more development teams to adopt ASPICE as part of an agile model.
Networking Within and Between Vehicles
Another standards issue within self-driving cars is networking among the large number of embedded systems that need to gather and process data and then use this data to execute control functions within a driverless vehicle. Vehicles will also need to communicate with other vehicles over a wireless vehicular ad-hoc network (VANET) using a standardized wireless protocol.
These self-driving cars will need to form an ad-hoc wireless network as they drive
There are already many standards that specify wireless access in VANETs, such as 2G-4G, WiMAX, DSRC, and WAVE. Existing MANET routing protocols and topologies are also being used to make routing decisions in networked vehicles. The IEEE 802.11p standard is typically used in experimental systems, and the use of this protocol for designing systems to network autonomous vehicles is a current research topic.
Networking within a vehicle should also focus on redundancy. If one ECU within a vehicle fails, those functions may need to be performed by another ECU, which requires an intra-vehicle network using a mesh topology to provide redundancy. Here, standard design rules for designing networked systems can be followed in terms of maintaining signal integrity, although these systems need to be extremely reliable to ensure safety. This is another aspect of self-driving cars that is seeing ongoing research.
Reliability Starts with Your Substrate
Automotive PCBs must survive in harsher environments than PCBs used in other applications. This includes passing thermal reliability and long-term stability tests in harsh environments. Meeting these reliability requirements starts with choosing the right substrate material.
PCBs in the engine compartment already need to withstand high temperatures, thus alumina or aluminum nitride ceramic substrates are typically used. FR4 is still the substrate of choice for safety systems. Metal core PCBs are typically used for anti-lock brake systems. The crash avoidance system in an autonomous car relies on LiDAR or radar, requiring PCBs with low losses at high frequency.
HDI design is also becoming more important as the number of components and interconnects used in PCBs for driverless cars will continue to increase. Infotainment systems are already becoming more complex as displays integrate more features, requiring greater integration without significantly increasing the size of the board.
Expect higher density than this in PCBs for self-driving cars
The power integrity and thermal requirements of PCBs in electric, hybrid, and fuel cell cars cannot be ignored. The industry is already using PCBs with heavy copper so that these boards can withstand higher current and higher temperature in charging, power management, and power distribution systems. Thermal management techniques will need to be used in these boards in order to prevent damage to components and the board itself.
Greater Integration in Self-Driving Cars
Going forward, we can expect to see greater integration of formerly disparate systems and greater processing power in vehicles. This requires integration among sensors, ECUs, and the various electromechanical systems that control all aspects of an autonomous vehicle. The software complexities are also increasing as the mass of data needs to be instantly used for object recognition, communication over VANETs, and plenty of other tasks in near real-time. The standards landscape will continue to change as the best designs prove their worth.
Greater integration within limited space will also require some level of miniaturization at the board, component, and interconnect levels. This is about more than aesthetics; the bulky systems used on experimental self-driving cars will need to be integrated inside the vehicle. This ensures that important systems can be adequately protected against harsh weather, mechanical vibration, and humidity. This will extend beyond the vehicle’s dashboard.
If your design team works on electronics for self-driving cars, then you need advanced PCB design software that allows your team to unleash their creativity while still complying with important automotive standards. Altium Designer® gives you a full suite of design and production planning tools, and all in a single program. You’ll have the freedom and tools you need to design electronics for any application.
About the AuthorMore Content by Zachariah Peterson