How Radar Technology is Driving SDV Safety & Comfort

Author : Matthias Feulner, NXP Semiconductors

16 April 2024

Figure 1: The distribution of radar sensor units around the vehicle for more comprehensive sensing capabilities
Figure 1: The distribution of radar sensor units around the vehicle for more comprehensive sensing capabilities

As vehicles become more connected, integration of numerous engineering advances is set to transform the whole driver experience. This article discusses how next-generation radar implementations will bring safety and comfort benefits to vehicle occupants, while also offering new growth opportunities for OEMs.

Since the late 1940s, car manufacturers have advertised the ultimate dream of freedom/enjoyment behind the wheel. At the same time, ensuring vehicle safety is another vitally important factor. In both cases, keeping within acute design constraints will prove challenging.
 
This is especially true as we enter into the age of autonomous vehicles, controlled largely by advanced software and computing technology rather than mechanical engineering alone. As features and vehicle functionality are managed through the software layer, greater customisation, personalisation and access over-the-air (OTA) updates will be become the norm, similar to what is generally being seen in the smartphone market.
 
Autonomous driving is at present being defined by 2 technologies. The 1st of these is vehicle-to-everything (V2X) communication, which uses wireless signals to transfer data between vehicles and also their surrounding objects/environs. Conversely, the 2nd which is advanced driver assistance system (ADAS) technology makes use of a diverse sensor suite, including built-in radar sensors, cameras and sometimes LiDAR imaging, so as to sense and map the surrounding environment.
 
The evolution of radar 
The use of radar will be of incredible value to automotive ADAS implementations. Either the 24GHz or 77GHz mmWave frequency bands can be employed. The technology involved has been evolving at a fast pace. Early iterations of radar sensors performed relatively simple functions mostly around safety (such as blind spot detection, collision avoidance, automated emergency braking, etc.). To meet the Euro NCAP 5-star rating, which primarily focuses on evaluating vehicle safety in terms of crash mediation and crash avoidance technologies, vehicles need to have blind spot detection sensors in their rear corners of the vehicle.
 
With previous generations of radar sensors suffering from low resolution and delivering relatively blurry renderings of surrounding scenes, radar technology was, for a time, considered a less than ideal solution for autonomous vehicles. Today, however, radar is a robust and cost-efficient RF sensor technology designed to serve mass deployment demands. This is not only for addressing NCAP safety functions, but also the sophisticated comfort functions associated with the fast-growing segment of vehicles that have SAE Level 2+ and Level 3 capabilities. These sensors offer detailed information about the vehicle’s environment for the construction of precise mapping, as well as radar-based object classification. In addition, a radar-based arrangement is far more effective than optical sensors (like cameras or LiDAR) when it comes to operation in adverse weather conditions.
 

Areas of growth for SDVs
The groundwork for software-defined vehicles (SDVs) has been laid, but technology is constantly moving forward. The next generation of SDVs are already under development and will enter production by 2027. These are set to take a completely new approach to radar sensor technology.
 
SDVs manage operations, add functionality and deliver new features entirely (or at least chiefly) through the software layer. Regular OTA updates will mean that software-defined features can change over the course of a vehicle’s lifetime - helping to enhance user experiences and prolong the usefulness of the vehicle. As a result, security around the software components of an SDV will clearly be critical to its reliability.
 
At the same time, radar sensor development will progress beyond primarily safety driven functions to offer a great array of comfort features. These will include everything from the highway pilot (where the vehicle takes over the driving controls on motorways or autobahns) and automated parking (where the vehicle handles all parking controls without the aid of the driver) through to traffic jam assistance and even urban control of the vehicle.
 
The new generation of SDVs won’t have radar features hosted on a single sensor. Rather, information will be leveraged from multiple sensor units mounted around the vehicle. Each of these will deliver detailed, rich, low level sensor data to a central ADAS control unit located in the heart of the vehicle.
 
This will enable vehicle manufacturers to implement more advanced capabilities than previously possible. For example, artificial intelligence (AI) may then be used for radar-based object classification. Feeding the sensor point cloud data through a neural network will enable the sensor to identify different objects in close proximity to the vehicle, differentiating a pedestrian from a bicycle, or a car from a truck. As the training is continuous, the software delivers an enhanced set of coefficients, which in turn creates ever-more reliable object classification. By sharing software upgrades as part of an OTA update, enhanced user experiences can be delivered over time.
 
Rather than updating each individual sensor, functionality can be updated in a single central place, making maintenance/upgrade work easier and more cost-effective. Consequently, vehicle manufacturers will be able to not only add new features, but also look to generate new revenue streams by offering users update subscriptions. 
 
By placing greater emphasis on the software layer of a vehicle, and essentially decoupling the functionality from the hardware layer, manufacturers will find that configuration management becomes a lot easier. Alterations to any of a vehicle’s configurations previously involved changing multiple individual controllers, but the new generation of SDVs enable changes to be made centrally, delivering the kind of flexibility that classical vehicle architectures did not provide.
  
Radar trends for SDVs 
By 2030, it is expected that the majority (or close to it) of vehicles will be supporting SAE Level 2+/3, while fully autonomous vehicles will continue to be a relatively small fraction of the market. Technologies initially experienced in the premium segment will start to appear in the mid-range segment, as costs and efficiencies improve. As a result, single-chip radar sensors addressing safety driven functions as well as advanced comfort features will proliferate widely.
 
Starting in 2025, mid-range vehicles are likely to come equipped with as many as 5 radar sensors - the 4 corner-deployed units plus 1 front-facing sensor. These will be enhanced by extended detection ranges to as much as 300m for the front radar sensor, and 200m for the corner sensors. This will enable the detection of objects further in the distance, adding greater safety capabilities to the vehicle.
 
In the premium segment of the vehicle market, the addition of even more radar sensors (as many as 10) will allow for multi-mode operation - where a sensor has different modes of operation, performing different functions at different times. Additionally, the inclusion of high-resolution sensing for the imaging radar sensor will mean vehicles can detect even smaller objects than previously possible, while simultaneously separating smaller objects reliably from larger ones, so it will be possible to identify a bicycle that is next to a large van, or a pedestrian standing alongside a car - thereby enhancing the safety for the driver and other road users. More importantly, high-resolution radar will enable essential functions for heightened levels of autonomous driving (such as radar-based object classification and free space mapping).
 
With the expected proliferation of sensors in both mid-range and premium vehicles, automotive OEMs are looking for a sensing solution that is scalable and will allow them to build compelling features - from the corner radar, through to the long-range front radar, and towards high-resolution 4D imaging radar implementations. Such technology should be based on a shared architecture, with common processing subsystems and common mmWave IPs across the different use cases, so as to offer optimal re-use of components and faster time to market.

Figure 2: Functional block diagram of NXP’s SAF86xx automotive radar sensor platform
Figure 2: Functional block diagram of NXP’s SAF86xx automotive radar sensor platform

Combining benefits of a common architecture and advanced process nodes 
Within such a common platform, best suited and most advanced process nodes should be employed for individual use cases - 28nm RFCMOS for radar transceivers and 16nm FinFET for processors. The benefit of switching to a 28nm RFCMOS single-chip transceiver device is the integration of the mmWave front-end with 4 transmit and 4 receive (4T4R) antennas, along with a multi-core processor subsystem, to create a significantly more compact sensor than previously possible. Form factors with dimensions as small as 5cm x 5cm have been demonstrated, which can easily be integrated into a wider range of vehicles. With future cars being connected to a mobile network, today’s radar chipsets are built to meet the latest security requirements through use of integrated hardware security engine (HSE) and media access control security (MACsec) engine mechanisms.
 
All these technologies are exemplified in the NXP SAF86xx one-chip automotive radar family. Each of the devices in this family brings together a high-performance radar transceiver, a multi-core radar processor and a MACsec hardware engine for state-of-the-art secure data communication over Automotive Ethernet. Combined with NXP’s S32 high-performance processors, vehicle network connectivity and power management, the full system solution paves the way for advanced, software-defined radar. It is intended to help vehicle manufacturers optimise next-generation ADAS partitioning in SDVs, while providing for a smooth transition to new architectures.

It is worth highlighting that NCAP regulations beyond 2025 look to significantly bolster the requirements for vulnerable road user detection, especially around 2-wheel vehicles (which will need to be detected at distances of between 140m and 200m). The enhanced capabilities of radar ICs now emerging will readily support manufacturers in meeting these requirements and further evolve the baseline of configurations over time.
 
In 2020, 120 million radar sensors were shipped. By 2025 this figure is predicted to rise to 200 million (according to Yole Group), and with ever-more advanced features as many as 400 million sensors might be shipped annually by the end of the decade. Driving this demand is the ever-present need for greater safety, but alongside that the evolution of radar technology will enable improved comfort for vehicle drivers and more flexibility for the manufacturers of such vehicles.


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