NXP: Integrated design approach for safety-critical real-time automotive systems

Until recently, only closed communication systems such as CAN-buses and Flexray networks have been applied in vehicles. Design of these closed networks is challenging because they are applied in a hostile environment (e.g., electromagnetic interference, wear due to vibration, etc.) and they directly affect the safety of the vehicle because they belong to the under-the-hood part, which controls the brakes, the suspension system, the power-steering system, and the engine.

In the near future, these closed systems will become open due to the envisioned introduction of intelligent traffic systems based on wireless communication (e.g. IEEE802.11p) for vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication. The envisioned objective is that these wireless communication systems will interact with the safety critical under-the-hood part of the vehicle, to realize a well functioning networked control system consisting of interconnected vehicles that is capable of optimizing traffic with respect to throughput, safety, and even fuel consumption. From both scientific and engineering perspectives new scientific challenges arise including the inherent uncertainty introduced by this wireless communication channel. Indeed, to create a reliable platoon of vehicles the information from the wireless communication system needs to be combined with the information
from other sensors such as radar and optical sensors. This information is used to make decisions based on the confidence level of the information, and provide appropriate control signals to, for example, accelerate or decelerate the vehicles (so-called cooperative adaptive cruise control (CACC) systems), which guarantee appropriate performance and safety under all conditions of a platoon.

The current industrial practice is that the safety critical wireless communication for V2V communication is designed independently of the rest of the system. Furthermore, the wireless
communication system is designed using techniques developed for non-safety critical car-entertainment systems. This holds for the hardware as-well-as the software of these systems. As a consequence, there is currently insufficient evidence that the safety requirements of an advanced driver assistant system such as the CACC will be met. This severely hampers the introduction of these systems in the market.

Problem and goal

Instead of considering the wireless communication system in isolation, we need to adopt an integrated multi-disciplinary design approach, taking into account the sensor fusion part, the control system, the adopted wireless communication medium in all its aspects, the physical behavior of the vehicles themselves and their environment. The envisioned design approach needs to be supported by formal models and analysis tools for the individual subsystems to guarantee functional and temporal correct behavior. To enable this, both advances in control theory, wireless modem design, and improved formal methods are needed. These advances have to be carefully tuned towards each other and combined leading to the desired integrated design approach.

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