Camera-monitor system camera-monitor system (CMS), or electronic rearview mirror, the camera imaging indicators requirements are much higher than other vehicle cameras, imaging effect to achieve or higher than the traditional optical rearview mirror reflection imaging effect, which puts forward very demanding requirements for the integration and mutual compatibility of imaging modules, ECU hosts, monitors.
What are electronic rearview mirrors?
The electronic rearview mirror, or Camera Monitor System, abbreviated as CMS, is literally called camera surveillance system. This concept has been around for a long time, replacing the traditional optical rearview mirror with a combination of camera + screen.
From its English literal meaning, CMS contains the current popular streaming media rearview mirrors, but at present, in the field of front loading in the industry, it is generally called CMS with electronic cameras to replace traditional optical exterior mirrors. Therefore, the electronic rearview mirror CMS is also called electronic side mirror, virtual reversing mirror, electronic reversing mirror, electronic replacement mirror, E-mirror.
Compared with the traditional optical exterior mirror, the electronic rearview mirror CMS has the advantages of a wider field of view, less affected by the weather, less wind resistance, and can be clearly seen at night when the lighting is insufficient, and has a broad application market in intelligent networked vehicles. At present, the CMS replacement of optical rearview mirrors is mainly implemented in Europe and Japan, and the domestic policy and regulations are limited, CMS only has a certain shipment in the field of commercial vehicles.
Honda e electronic rearview mirror
In general, in order to ensure clear and accurate images, electronic rearview mirrors need to have more complex hardware and software support than traditional optical rearview mirrors:
Hardware: Basic configurations such as HD wide-angle camera/multi-camera/lens stabilization/night vision/fog-breaking function are required.
Software: It is necessary to consider a series of problems such as picture delay/ image distortion reduction / stitch distortion correction / number of frames played / transmission rate, which poses higher challenges for processing terminals.
Hyundai Ioniq 5
Advantages of electronic rearview mirrors
However, compared to traditional optical exterior mirrors, the advantages of CMS are very obvious:
Lower wind resistance/wind noise: Since the external device of the electronic rearview mirror has only a camera, its volume can be reduced to one-third (or even smaller) of that of a traditional rearview mirror, and the overall design can be more aerodynamic, in addition, high-speed wind noise will also be reduced a lot.
Audi e-tron
Wider field of view: Conventional optical mirrors have a fixed curvature, shape, and size, and a limited field of view area. Through the use of different sensors and cameras at 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 mirrors for Lexus ES
Small affected by the weather: the electronic rearview mirror only needs to do a good job of lens hydrophobic waterproof function, the rest is done by the post-algorithm and the display in the car, even if it is bad weather, the rear screen is still clearly visible.
Reduce the adverse effects of light: First, due to the night vision lens, the rear field of view is still visible in the case of insufficient illumination; in addition, when exposed to strong light (such as high beams behind the night), the glare can be eliminated by algorithms, etc.
Electronic rearview mirrors are currently struggling
Of course, the electronic rearview mirror is not only an advantage, the following problems also need to be further improved.
High cost: The hardware and software structure of electronic rearview mirrors is complex, so the current cost is high.
Reliability problem: electronic rearview mirror, its reliability is certainly not as good as the traditional mechanical structure. On the other hand, the electronic rearview mirror needs to work continuously from the start of the vehicle, the long working time, coupled with the harsh environment outside the car, the stability of the product is worrying. Once the camera is damaged or the display screen freezes during the vehicle's driving, it will seriously affect the driving safety.
Interference problems caused by line of sight shifting: The installation position of the existing display screen will be different from the traditional optical rearview mirror, in addition, the driver's observation of the front field of view and the focus of the observation display are not consistent, which is easy to cause eye fatigue.
Domestic policies and regulations do not allow pure CMS mass production, on the whole, electronic rearview mirror CMS compared to traditional optical rearview mirrors still have obvious advantages. However, due to the safety regulations of different regions, in addition to the concept car, only a small number of production models in the Japanese or European markets are currently equipped, such as the Lexus ES and Audi E-Tron, which were launched in 2018, and the Mercedes-Benz commercial vehicle Actros also appears.
While regulations on electronic rearview mirrors have not yet been liberalized in most regions, many car companies are actively promoting it: In March 2014, a coalition of automakers such as GM, Volkswagen and Toyota joined Tesla in petitioning the National Highway Traffic Safety Administration to use camera-based rearview and side-view systems. In 2015, Daimler made a similar proposal, the company wanted to replace the traditional rearview mirrors with cameras on heavy-duty trucks.
The BMW i8 concept car of 2016
In China, it maintains a more rigorous attitude towards CMS. The CMS is an indirect viewing device that does not allow the direct replacement of traditional optical rearview mirrors for the time being. The good news is that it is understood that GB 15084 "Performance and Safety Requirements for Indirect Vision Devices for Motor Vehicles (Draft for Approval)" is expected to be released in mid-2022, and the CMS market may quickly enter the mass production stage.
Reproduced from the Intelligent Car Club, the views in the article are only for sharing and exchange, and do not represent the position of this public account, such as copyright and other issues, please inform, we will deal with it in a timely manner.
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