Application of Car Camera: Development Status of Electronic Rearview Mirrors

As the core sensor of car perception, the camera mainly obtains image information to serve various functions of ADAS. The current popular application scenarios for in car cameras include: automatic parking, blind spot monitoring BSD, ACC/FCW/LKA, driver monitoring DMS, etc. In addition to the above applications, electronic rearview mirrors are also a point of great concern to everyone. Below, the editor will take you to understand them together.

The concept of electronic rearview mirrors has existed for a long time, also known as rearview mirror cameras, which replace traditional optical exterior rearview mirrors with a combination of cameras and screens. Generally speaking, to ensure clear and accurate images, electronic rearview mirrors require more complex hardware and software support:

In terms of hardware, basic configurations such as high-definition wide-angle camera/multi camera/lens stabilization/night vision/fog breaking function are required.

In terms of software, it is necessary to consider a series of issues such as image delay, reduction of image distortion, correction of stitching distortion, playback frame rate, and transmission rate, which pose higher challenges for processing terminals.

But compared to traditional optical exterior mirrors, its advantages are very obvious:

Lower wind resistance/wind noise: Due to the external device of the electronic rearview mirror only having a camera, its volume can be reduced to one-third (or even smaller) of traditional rearview mirrors, and the overall design can be more in line with aerodynamic principles. In addition, high-speed wind noise will also be significantly reduced.

A wider field of view: Traditional optical mirrors have fixed curvature, shape, and size, and a limited field of view. 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.

Less affected by weather: The electronic rearview mirror only needs to have a hydrophobic and waterproof lens function, and the rest is completed by post-processing algorithms and the display screen inside the car. Even in severe weather, the rear image is still clear and visible.

Reduce the adverse effects of light: Firstly, due to the installation of night vision lenses, the rear view is still visible in situations of insufficient lighting; In addition, when exposed to strong light (such as high beams behind at night), dazzling can be eliminated through algorithms and other methods.

Of course, electronic rearview mirrors not only have advantages, but the following issues also need further improvement.

High cost: The software and hardware structure of electronic rearview mirrors is complex, therefore, the current cost is very high.

Reliability issue: Electronic rearview mirrors are definitely not as reliable as traditional mechanical structures. On the other hand, electronic rearview mirrors need to work continuously since the vehicle is started, with a long working time, and coupled with the harsh environment outside the car, the stability of the product is worrying. Once the camera is damaged or the display screen crashes while the vehicle is in motion, it will seriously affect driving safety.

Interference caused by line of sight transfer:

Compared to traditional optical rearview mirrors, the installation position of existing display screens may have certain differences. In addition, the driver's observation of the front field of view is not consistent with the focal length of the display screen, which can easily cause eye fatigue.

Overall, electronic rearview mirrors have significant advantages compared to traditional optical rearview mirrors. However, due to safety regulations in different regions, except for concept cars, only a few mass-produced models in the Japanese or European markets are currently equipped with it. For example, the Lexus ES and Audi E-Tron, which were launched in 2018, have also appeared on Mercedes Benz's commercial vehicle Actros.

Although regulations on electronic rearview mirrors have not yet been lifted in most regions, many car companies are actively promoting them. In March 2014, a consortium of car manufacturers including General Motors, Volkswagen, and Toyota, together with Tesla, petitioned the National Highway Traffic Safety Administration in the United States to use camera based rearview and side view systems. In 2015, Daimler also made a similar suggestion, hoping to replace traditional rearview mirrors with cameras on heavy trucks.

For China, progress seems to be accelerating: it is understood that the "GB 15084-2013 Performance and Safety Requirements for Indirect Vision Devices in Motor Vehicles" is being expanded, and at the same time, the draft for soliciting opinions on the industry standard "Streaming Media Rearview Mirrors for Automobiles" has also been released.