(Wen / Zhou Kaiyang) with the national policy and the launch of several L3 models, 2020 to 2030 will become the “golden decade” of automatic driving in China, and the realization of this vision is inseparable from the on-board advanced driving assistance system (ADAS). Adas includes adaptive navigation, automatic parking, blind spot monitoring and other functions. The components used include lidar, millimeter wave radar, camera and navigation system.
Adas systems on the market are mainly divided into vision leading systems composed of radar and camera, and laser radar leading systems, but both systems are inseparable from the key millimeter wave radar. Electronics enthusiasts interviewed Huang Mingda, chief system architect of NXP automotive electronics in Greater China, and Liu Hongquan, marketing director of Gartland microelectronics. Two authorities in this field analyzed the current situation and future of millimeter wave radar.
In 2019, China equipped 5.17 million millimeter wave radars on passenger cars, a year-on-year increase of 44.37%. Due to its higher applicability, the market penetration is also higher than that of lidar and ultrasonic radar. Dr. Huang Mingda of NXP said that millimeter wave radar is also in a period of rapid growth. It is expected that the compound annual growth rate worldwide from 2017 to 2025 will exceed 25%, and even more than 30% in China. Liu Hongquan, marketing director of Gartland microelectronics, believes that in recent years, the automatic driving market belongs to the stage from 0 to 1, and it is indeed a window of rapid growth for ADAS. Since last year, the trial operation of robotaxi has been started, such as waymo abroad and wenyuanzhixing in China.
Advantages and disadvantages of different ADAS sensors
From the models that have been launched and even mass produced, there are both factions loyal to millimeter wave radar + camera, such as Tesla, and factions dominated by lidar, such as waymo. Although the two factions have more or less added millimeter wave radar to their plans, what is the difference between them and lidar?
Performance comparison of different ADAS sensors
Dr. Huang Mingda mentioned that the main advantage of millimeter wave radar is all-weather, so it will occupy an important position in ADAS / ad systems from L1 to L5. At this stage, the L1 / L2 level ADAS system is mainly composed of millimeter wave radar and camera. Millimeter wave radar can detect the range, speed and angle of targets, while the camera can identify traffic signals and lane lines and semantic segmentation of scenes. The combination of the two can achieve relatively stable target detection, tracking and classification. It can meet the system requirements of L2 + level ADAS in terms of vehicle book, vehicle regulation certification and applicability. Due to its high angular resolution, lidar has great advantages in self positioning and map construction. Therefore, the two automatic driving systems above L3 may form mutually redundant systems with millimeter wave radar, camera, ultrasonic radar and other sensors. However, lidar still faces many challenges in vehicle regulation certification and vehicle book.
Huang Mingda, chief system architect of NXP Greater China Automotive Electronics
Millimeter wave radar has many parameters, of which the most intuitive is its detection range. So how much detection distance does it need to achieve in the current L1 / L2 ADAS system requirements? Liu Hongquan analyzed this problem. For rear angle radars commonly used for blind zone detection (BSD) and lane change assistance (LCA), the requirement for the longest detection distance is not high. For example, for LCA applications, only 70 meters is enough. The forward radar needs a relatively large detection range. In the current more advanced forward millimeter wave radar, the farthest detection range has been more than 250m. The requirements of minimum detection distance vary according to the application scenario.
Liu Hongquan, marketing director of Gartland Microelectronics
However, both respondents also mentioned that the detection distance is not the only parameter to determine the performance of millimeter wave radar. Huang Mingda said that in higher-level automatic driving, the range resolution, detection speed range and resolution, detection angle and resolution will also be further improved.
24GHz vs 77GHz band dispute
At present, in ADAS application scenarios, the commonly used millimeter wave radar frequency band is divided into 24GHz and 77GHz. Which frequency band will be the future development direction?
Many millimeter wave radar products in the 24GHz band have emerged in the domestic market. However, due to the spectrum rules and standards formulated by the European Telecommunications Standardization Association (ETSI) and the Federal Communications Commission (FCC), the 24GHz UWB band (21.65-26.65ghz) will soon be phased out. After January 1, 2022, UWB band will not be used in Europe and the United States, and only narrowband ISM band (24-24.25ghz) can be used for a long time.
Wavelength at different frequencies
Therefore, most manufacturers are shifting their development focus to 77GHz. In 2019, the assembly rate of domestic 77GHz millimeter wave radar also increased by 69.3% year-on-year. Huang Mingda explained that from the basic principle of radar, 77GHz has smaller wavelength and larger available bandwidth than 24GHz. The resolution of 77GHz radar in three aspects of range, speed and angle is much higher than 24GHz. This performance improvement can meet the continuous improvement of new vehicle crash test (NCAP) requirements in various countries and regions, such as the evolution from simple AEB function to pedestrian AEB under low light conditions, and then to AEB that can avoid steering. NXP has also realized the transformation from SiGe to RFCMOS in semiconductor technology, which not only ensures the performance, but also greatly reduces the cost and power consumption. In addition, the performance of signal processing chip has been improved, and the cost of 77GHz millimeter wave radar has reached an acceptable level for ordinary cars.
With the increase of millimeter wave radar assembly rate, the mutual interference of radars in the same frequency band has become one of the challenges in the design of ADAS system. Many radar suppliers and OEMs began to add anti-jamming improvements to algorithms and hardware.
Combination and complementarity with Internet of vehicles technology
On the road of realizing automatic driving, the Internet of vehicles is also an indispensable part. The Internet of vehicles promoted by China is c-v2x with 4G / 5G and other cellular communication technologies as the core, so how can millimeter wave radar integrate with this technology?
On this issue, Liu Hongquan of Gartland microelectronics believes that most of the millimeter wave radars assembled today still operate independently, but v2x and other vehicle networking technologies are indeed the future direction of automatic driving. Through the information exchange between vehicles, the “field of vision” obtained by a single vehicle ADAS is expanded. Huang Mingda of NXP also added an application scenario within such “non sight distance”: ambulances on mission can transmit this information to the measurement in all directions of distant intersections through v2x, so that they can prepare to avoid in advance. It can be seen that v2x vehicle networking technology will complement sensors such as millimeter wave radar, so as to achieve a higher level of automatic driving.
With the continuous improvement of the performance requirements of ADAS, the number of on-board sensors is also increasing. Sony’s vision-s concept car on display at CES this year is loaded with 33 sensors, including lidar, millimeter wave radar and ultrasonic radar. The recently released Xiaopeng P7 is also equipped with 13 cameras, 5 millimeter wave radars and 12 ultrasonic radars. So is the future trend to add more millimeter wave radars to ADAS system?
Number of sensors used in different levels of automatic driving / NXP
Both respondents believe that the number and performance of millimeter wave radar will be further improved in higher-level automatic driving. Liu Hongquan believes that unlike mechanical radars, the number of millimeter wave radars will continue to increase in order to cover the detection range of 360 °. In the automatic driving at L3 level, some traditional sensors may also be replaced by millimeter wave radar.
Market trend after the epidemic
While the global automobile production was affected by the epidemic, the two respondents also gave their own judgment on the trend of millimeter wave radar market. Dr. Huang Mingda believes that with the continuous implementation and strengthening of policies and regulations such as new car crash test (NCAP) in various countries, the market penetration of millimeter wave radar will continue to improve on the whole. Some organizations predict that the insurance volume of new vehicles with L1 / L2 ADAS will increase from 10% at the beginning of 2020 to 25% at the end of the year. In addition, in the long run, because millimeter wave radar can be applied to all levels of L1-L5 automatic driving system, it is an integral part of it. With the continuous evolution of automatic driving and the enhancement of system requirements, the demand for millimeter wave radars will continue to improve.
Liu Hongquan believes that the domestic auto market has begun to rebound strongly, with a very large increase month on month. Millimeter wave radar customers have not been greatly affected. Although car sales have declined to a certain extent, with the increase of millimeter wave radar assembly, the overall trend is still showing a good upward trend.
On February 28 this year, the national development and Reform Commission, together with 11 national ministries and commissions, issued the intelligent vehicle innovation and development strategy, which gives the vision of realizing the large-scale production of conditional intelligent vehicles in 2025 and the full completion of China’s standard intelligent vehicle system in 2035. During this period, as a link closely connected with automatic driving, the millimeter wave radar market will also take advantage of the situation to achieve rapid growth and promote the rapid landing of the intelligent vehicle industry.