Application of Ultrasonic Radar in Automobiles Analysis of Main Vision Sensors in ADAS Systems

▲Application of millimeter-wave radar in ADAS system

The key technologies of millimeter-wave radar are monopolized by foreign companies, with a high degree of concentration. In the global millimeter-wave radar market, the dominant countries are Germany, the United States, Japan and other countries. At present, millimeter-wave radar technology is mainly monopolized by traditional component giants such as Continental, Bosch, Denso, Autoliv, Denso, Delphi and other companies; among them, 77GHz millimeter-wave radar technology is monopolized by companies such as Bosch, Continental, Delphi, Denso, TRW, Fujitsu Ten, Hitachi and others. In 2016, Bosch and Continental both had a global millimeter-wave radar market share of 17%, ranking first; Denso and Hella ranked second with a market share of 11%, ZF accounted for 8%, Delphi accounted for 6%, and Autoliv accounted for 4%. The top seven supplier giants have a market share of 73%.

▲Major overseas suppliers and products of millimeter wave radar

Domestic millimeter-wave radars rely on imports and are limited by foreign technology blockades. 24GHz millimeter-wave radars are the mainstream direction. At present, all millimeter-wave radar sensors installed in mid-to-high-end cars in the Chinese market rely on foreign imports. The market is monopolized by American, Japanese and German companies, and the prices are expensive. They have also adopted technology blockades, and independent control is imminent. Domestic independent automotive millimeter-wave radar products are generally still in the development stage. Considering the R&D costs and the limited 77GHz development technology, domestic manufacturers are currently focusing on 24GHz for millimeter-wave radar research. In the domestic market, the product system of 24GHz millimeter-wave radars is relatively mature, the supply chain is relatively stable, and the core chips of 24GHz can be obtained from chip suppliers such as Infineon and Freescale. According to the research of Mems Consulting, the number of pre-installed millimeter-wave radars in Chinese cars reached 1.05 million in 2016, of which 24GHz radars accounted for 63.8% and 77GHz radars accounted for 36.2%.

According to estimates, the market size of millimeter-wave radar will reach 470 million yuan, 3.6 billion yuan and 8 billion yuan in 2019, 2020 and 2025 respectively. The compound growth rate from 2017 to 2025 will reach about 58%.

2. LiDAR: The key to L3-L5 autonomous driving

LiDAR is a comprehensive light detection and measurement system that transmits and receives laser beams, analyzes the return time after the laser encounters the target object, and calculates the relative distance between the target object and the vehicle. Currently, 8-line, 16-line, and 32-line LiDARs are common. The more LiDAR beams there are, the higher the measurement accuracy and the higher the safety. LiDAR is not new and has long been used in aerospace, surveying and mapping and other fields. With the development of automotive intelligence, LiDAR has begun to be used in L3 autonomous driving. Due to its high precision and real-time 3D environment modeling, it will become the most critical sensor in the L3-L5 stage.

▲The working principle of LiDAR

▲Velodyne HDL-64E LiDAR 3D imaging

Solid-state LiDAR is the future trend, with advantages of miniaturization and low cost. There are two main ways to reduce the cost of LiDAR in the industry:

1) Eliminating the mechanical rotating structure and adopting solid-state technology fundamentally reduces the cost of LiDAR. Solid-state LiDAR is smaller in size, easier to integrate, and has improved system reliability, so LiDAR has a trend towards solid-state development.

2) Reduce the number of laser radar lines and use multiple low-line laser radars in combination. From mechanical rotary to hybrid solid-state to pure solid-state laser radars, with the expansion of mass production scale and the iteration and update of technology, the cost continues to decrease, and laser radar is also constantly developing towards miniaturization, low power consumption and integration.

The core technology of LiDAR is mainly mastered by Velodyne, Ibeo and Quanergy. Velodyne of the United States started early in the development of mechanical LiDAR and has advanced technology. It has recently launched the 128-line prototype product VLS-128. It has also established cooperative relationships with global leading autonomous driving companies such as Google, General Motors, Ford, Uber, and Baidu, and has occupied most of the market share of automotive LiDAR.

Google, Baidu, Ford, Audi, BMW and other companies have successively adopted LiDAR perception solutions. BMW announced that it will join hands with LiDAR startup Innoviz to develop driverless cars, which are expected to be launched in 2021. According to the prices of LiDAR products on the official websites of various companies, the value of a single vehicle LiDAR sensor is between 30,000 and 80,000 US dollars.

In the short term, LiDAR will not be widely used in the automotive field. Although the accelerated development of autonomous driving has created good application prospects for the LiDAR industry, many pain points in the development of LiDAR itself have limited its application in autonomous vehicles. There are three main limiting factors:

1) High cost. Velodyne, the leading LiDAR company, charges $8,000 for its 16-line product, $40,000 for its 32-line product, and about $80,000 for its 64-line product. The high product price also inhibits the application of LiDAR in autonomous vehicles.

2) Difficult to mass produce and long delivery cycle. Velodyne's 64-line product production cycle takes 4-8 weeks, and 32-line and 16-line products take 2-4 weeks. In order to ensure the accuracy of the laser radar transmission and reception signal, its complex assembly and adjustment process lengthens its delivery cycle.

3) Lack of relevant vehicle regulations. Currently, autonomous driving is only a forward-looking concept that has not been put into practice. There are no mandatory requirements for corresponding policies and regulations, which to some extent limits the popularity of lidar in the field of autonomous driving.

3. Ultrasonic radar: mainstream sensor for automatic parking systems

The working principle of ultrasonic radar is to measure the distance by the time difference between the ultrasonic wave emitted by the ultrasonic transmitter and the time when the ultrasonic wave is received by the receiver. In autonomous driving, the basic application of ultrasonic radar is parking assistance warning and car blind spot collision warning. Ultrasonic radar has low cost and advantages in short-distance measurement. The detection range is between 0.1-3 meters and the accuracy is high, so it is very suitable for parking. However, the measurement distance is limited and it is easily affected by bad weather.

▲Working principle of ultrasonic radar

The popularity of automatic parking has stimulated the demand for ultrasonic radar. Ultrasonic radar is generally installed on the bumper or side of the car. The former is called UPA, which is generally used to measure obstacles in front and behind the car, and the latter is called APA, which is used to measure side obstacles. APA ultrasonic sensor is the core component of the automatic parking assistance system. It has a long detection distance and can be used to detect the width of the parking space and obtain the parking space size and vehicle location information. Ultrasonic radar is mainly used for reversing radar and close-range obstacle monitoring in automatic parking systems. Reversing radar has been lowered from high-end models to mid- and low-end models, with a high penetration rate and a pre-installation rate of about 80%. The reversing radar system usually requires 4 UPA ultrasonic radars, and the automatic parking radar system requires 6-12 ultrasonic radars. The typical configuration is 8 UPA + 4 APA.

▲Application of ultrasonic radar in automobiles

▲Comparison of UPA and APA ultrasonic radars

Ultrasonic radar technical solutions have their own advantages and disadvantages, and analog radar occupies the main market. There are generally four technical solutions for ultrasonic radar: analog, four-wire digital, two-wire digital, and three-wire active digital. The signal interference processing effect is improved in turn. The four technical solutions have their own advantages and disadvantages in terms of technical difficulty, assembly, and price. At present, the "analog" technical route is more commonly used in the market. Its advantage is low product cost, but it is easily affected by external environment. With the trend of intelligence in the future, the "digital" technical route will be more popular. Under the "digital" technical route, signal digitization can greatly improve the radar's anti-interference ability, but the cost is high and the technical difficulty is high. At the current stage of technological level, most of them can only adopt the four-wire approach.

▲Four technical route solutions for ultrasonic radar

The ultrasonic radar market is mainly occupied by BOSCH, Japan's Murata, Japan's Nicera, etc., and domestic Audiway and Tongzhi Electronics are highly competitive. Audiway is a leading domestic ultrasonic sensor manufacturer. In 2016, Audiway's sales of automotive ultrasonic sensors were 26.27 million. The global market capacity of automotive ultrasonic sensors is about 274 million. Audiway's automotive ultrasonic sensors account for 9% of the global passenger car market share. Audiway's largest customer is Taiwan Tongzhi Electronics. Taiwan Tongzhi Electronics' core product is reversing radar, and its market share ranked first in Asia in 2016.

The ultrasonic market is expected to continue to grow in the short and medium term, and may face replacement pressure from other radar sensors in the long term. At present, the rear-facing ultrasonic radar has the highest installation rate, reaching 45.2%, the "forward + rear-facing radar" installation rate is 28.3%, and the proportion of no installation is 26.5%. With the development of automated driving, "forward + rear-facing" radar is expected to become standard. Therefore, it is expected that in the short and medium term, the market penetration rate of ultrasonic radar will continue to increase, but in the long run, in the future, in high-level autonomous driving models, some or all of the ultrasonic radars will be replaced by millimeter-wave radars, lidars, etc. with better comprehensive performance.