As the core sensor of vehicle perception, the camera is mainly used to obtain image information for various functions of ADAS. At present, the popular application scenarios of on-board cameras include: automatic parking, blind spot monitoring BSD, ACC/FCW/LKA, driver monitoring DMS, etc. In addition to the above applications, the electronic rear-view mirror is also a point of great concern. Now, I will take you to learn about a revolutionary application of the car camera: the electronic rear-view mirror CMS.

1、 What are electronic rear-view mirrors?

Electronic rear-view mirror, namely Camera Monitor System, is abbreviated as CMS, which is called camera monitoring system in literal translation. This concept has existed for a long time. It uses the combination of camera and screen to replace the traditional optical rear-view mirror.

From its English literal meaning, CMS includes the popular streaming media rearview mirror at present. However, in the front mounting field of the industry, it is generally called CMS when electronic cameras replace traditional optical rearview mirrors. Therefore, the electronic rear-view mirror CMS is also called electronic side mirror, virtual reversing mirror, electronic reversing mirror, electronic replacement mirror, and E-mirror.

Honda e electronic rearview mirror

Generally speaking, in order to ensure clear and accurate images, electronic rear-view mirrors need more complex hardware and software support than traditional optical rear-view mirrors:

Hardware: HD wide-angle camera/multi camera/anti shake lens/night vision/fog breaking function and other basic configurations are required. Software: a series of problems need to be considered, such as picture delay/image distortion reduction/mosaic distortion correction/number of playing frames/transmission rate, which pose a higher challenge to the processing terminal.

Modern Ioniq 5

2、 Advantages of electronic rear-view mirror

However, compared with traditional optical exterior rear-view mirrors, CMS has obvious advantages:

Lower wind resistance/wind noise: Since the external equipment of the electronic rear-view mirror is only a camera, its volume can be reduced to one third (or even less) of the traditional rear-view mirror, and the overall design can be more consistent with aerodynamic principles. In addition, the high-speed wind noise will also be reduced.

Audi e-tron

Broader vision: The curvature, shape and size of traditional optical mirrors are fixed, and the field of vision is limited. By using different sensors and cameras from different angles, we can get more images and even focus on a certain area to ensure the safety of vehicles and other road participants.

Electronic rearview mirror of Lexus ES

Less affected by weather: The electronic rear-view mirror only needs to do a good job of hydrophobic and waterproof function of the lens, and the rest is completed by the later algorithm and the display screen in the car. Even in bad weather, the rear image is still clearly visible.

Reduce the adverse effects of light: First, due to the night vision lens, the rear field of vision is still visible in the case of insufficient lighting; In addition, when exposed to strong light (such as the high beam behind at night), dazzle can be eliminated through algorithms.

Electronic rearview mirror of Lexus ES

3、 Current difficulties of electronic rear-view mirror

Of course, electronic rear-view mirrors have more than just advantages. The following problems also need to be further improved.

High cost: The software and hardware structure of electronic rear-view mirror is complex, so the current cost is very high.

Reliability issues: The reliability of electronic rear-view mirror is certainly not as good as that of traditional mechanical structure. On the other hand, the electronic rear-view mirror needs to work continuously since the vehicle starts, and the working time is long. In addition to the harsh environment outside the vehicle, the stability of the product is worrying. However, once the camera is damaged or the display screen crashes during driving, the driving safety will be seriously affected.

Interference caused by sight shifting: The installation position of the existing display screen is different from that of the traditional optical rear-view mirror. In addition, the focus of the driver's front view is not consistent with that of the display screen, which is easy to cause eye fatigue.

Domestic policies and regulations do not allow pure CMS mass production, On the whole, the electronic rear-view mirror CMS has obvious advantages over the traditional optical rear-view mirror. However, due to the safety regulations in different regions, in addition to concept vehicles, only a few mass production models in Japan or Europe are equipped at present, such as Lexus ES and Audi E-Tron, which were launched in 2018. In addition, Mercedes Benz's commercial vehicle Actros also appears.

Although the regulations on electronic rear-view mirrors have not been released in most regions, However, many automobile enterprises are actively promoting: In March 2014, an alliance composed of GM, Volkswagen, Toyota and other automobile manufacturers, together with Tesla, petitioned the National Highway Traffic Safety Administration to use the camera based rear view and side view systems. In 2015, Daimler also made a similar proposal. The company hopes to use cameras instead of traditional rear-view mirrors on heavy trucks.

BMW i8 concept car in 2016

When dealing with CMS in China, it maintains a more rigorous attitude. CMS is an indirect vision device, which is not allowed to directly replace the traditional optical rear-view mirror for the time being.

4、 Who is making the electronic rearview mirror

OEM: Currently, the released mass production CMS models are mainly in Europe and Japan, including Lexus ES300h (Japan), Audi e-tron (Europe), Honda e (Japan), Mercedes Benz Actors Heavy Truck (Europe), Manny Opland Bus (Europe), Duff XG+, Volvo, etc.

Limited by policies and regulations, the current domestic commercial vehicle intelligence adds CMS configuration to the traditional optical rear-view mirror to supplement the vision, such as BYD's K9 pure electric, BYD B12/B12D, Shaanxi Automobile X6000 tractor, Liuqi Chenglong H7, etc.

In the field of passenger cars, there has not been a CMS model mass produced in China, and many concept cars have been produced, such as Weima, Landu, Zhiji, SAIC R, BYD, etc. But at present, the fastest mass production may be the Beijing Rubik's Cube released at last year's Guangzhou Auto Show. When the GB 15084 standard mentioned above is released, the Beijing Rubik's Cube may become the first passenger car equipped with CMS in China.

Beijing Rubik's cube electronic rearview mirror

spare parts: All car manufacturers are working hard to seize the first launch of domestic passenger car CMS. And for the parts enterprises supplied by CMS system, it has also been laid out for a long time. At present, leading enterprises in the industry include: Mecron, Bosch, Valeo, ficosa, Tokai RIKA, Samvardhana Motherson Group, Yuxing Electronics, Yuanfeng Technology, Qingdao Jidong, Huayang, Jiangcheng, Hangsheng, Desai Xiwei, Guangzhou Rongsheng, etc.