What is the difference between AEB products with camera and millimeter wave radar as the core technology?
What is AEB? AEB is the abbreviation of AutomaTIc Emergency Braking. The Chinese translation is called "automatic emergency braking". This technology can be described as the "fuse" of the intelligent car at present. It is because of its appearance as the "brake assist system" for the first time in the car. Now we can see the intelligence represented by autonomous driving and car networking. Technology is on the top of the car. Moreover, the core technology for automatic emergency braking is still the basis for helping cars “try†automatic driving.
At present, there are two main mainstream technologies for implementing AEB. The first one is to collect images by a monocular/binocular camera, to identify obstacles and to make a “visual faction†of braking commands. The second is to determine front obstacles by millimeter wave radar. Object, measure the relative movement trend of obstacles and make a "radar pie" for braking commands.
At present, these two AEB factions have their own product representatives, such as Tesla is the "golden card member" of "Radar." Coincidentally, at the site of the annual meeting of the China Automotive Engineering Society in 2016, the car cloud bacteria encountered the Bosch AEB test car and the AZ AEB test car using these two technologies. Please see the car cloud bacteria site. Experience report.
First, announce the test results of two AEB test cars here:
After at least 3 standardized tests (at 40kM/h speed, facing obstacles) for each test vehicle, they did not find any "mistakes" in the collision target obstacle after emergency braking, although the car cloud The ribs were repeatedly "sled" by the seat belt during the multiple automatic emergency braking, but we saw that the target dummy and the fake car were still safe and sound, and we felt that it was worth it.
From a technical point of view, the Bosch AEB uses a binocular camera (detection range is 45 degrees horizontally, 24 degrees vertically, and the longest detection distance is 120 meters). The advantage is that it can directly capture image information just like the human eye, fast enough in hardware. Today, the binocular camera can capture almost all the key information in the field of view, and calculate the parallax of the two images according to the visual algorithm to get the distance result of the object. In theory, the binocular camera is more accurate and faster than the monocular camera in close range.
In communication with engineers, it is known that Bosch's system has been applied to some foreign models. It can not only identify adults and children, but also identify people who are playing umbrellas or running, such as the old driver's most worried. "Ghost probe" problem, this system can be well prevented under certain conditions.
At the same time, relying on the advantages of the binocular camera, Bosch's AEB system can also add lane departure warning, lane keeping and automatic high beam.
However, it is precisely because of the excellent imaging recognition capabilities that Bosch's visual AEB system has shortcomings under certain conditions. For example, the binocular AEB system has fixed requirements for the placement position, which will result in a blind spot in front of the vehicle, and the AEB system will not respond to any obstacles in the blind zone.
In addition, in special circumstances such as blizzard, heavy rain, low light environment or strong light, Bosch's AEB system will increase the probability of misjudgment or missed judgment. After all, in these cases, the human eye has the ability to recognize. The problem of falling, let alone the camera.
But the "visualist" AEB has a short board area, but it is just a good place for the "radar" AEB to show its talents:
Suzhou Anzhi uses the 77GHz millimeter wave radar on the AEB test car. This system can not only filter the adverse effects caused by bad weather, but also has a farther detection range, faster discovery of potential targets and more accurate distance determination. However, since the millimeter-wave radar can only "judge" the obstacle and cannot recognize the "obstacle", there is no room to support the lane departure warning, but it can achieve the ACC function.
At the same time, a congenital weakness of the millimeter-wave radar may not be known to many people: due to the particularity of the working principle, the millimeter-wave radar has a slightly lower recognition rate for moving objects perpendicular to the direction of motion of the vehicle. That is to say, when a vehicle, pedestrian or other object is inserted horizontally in front of the vehicle, the millimeter wave radar may not be recognized. For example, when driving everyday, if a car is at the same speed as you, slowly inserting it in front of your front, the AEB working on your car with millimeter-wave radar may not recognize the new car unless it is with you. Produces a longitudinal change in distance.
At present, AEBs based on “visual pie†and “radar pie†have their own weaknesses, but at the same time they complement each other. So some manufacturers began to introduce AEB systems that combine the two technologies. But the biggest difficulty with this seemingly "perfect" AEB system is the analysis of the data obtained by two different sensors and the application of the only correct command.
At the moment, Bosch’s “visualist†AEB is designed for “weak road users†– protecting pedestrians, although its existing technology can already identify other vehicles, signs and lanes in the field of vision, but emergency The action will only trigger if a pedestrian collision is detected. And Azhi's "radar" AEB is aimed at car development, and when it detects pedestrians or other objects, it will not take active braking measures. At present, the purpose of such a setting is to reduce the sensitivity of the system and avoid the "sad reminder" of the driver's dashed line in the city. And the best condition of the two systems at present is that the speed does not exceed 40kM/h. If this speed is exceeded, the vehicle cannot be completely stopped, and only the damage caused by the collision can be reduced.
AEB models on the market
At present, there are still a lot of production cars equipped with "Vision" and "Radar" AEB, such as Tesla, Volvo's XC90 and GM's new LaCrosse. They are all equipped with camera and millimeter wave radar technology. "Comprehensive" AEB products. However, on these models, AEB exists only as an integral part of the vehicle's ADAS system.
Help the driver to make decisions
In effect, the AEB system is pursuing a result that helps the driver make the right decisions and reduce the driver's workload. However, subject to the limitations of real technology, some poor driving conditions or very special circumstances, the AEB system may become the source of insecurity.
For example, the two AEB test cars tested by the car cloud bacteria may cause the rear car to chase after the emergency brakes to avoid the front obstacles. If the rear is driving a large cargo, is it not urgent? Is it safer to brake and consider other options (for the driver)?
For example, on some roads with low adhesion such as ice, snow, and water, the existing AEB cannot identify the road surface. Therefore, when the AEB is working, the strong emergency braking is likely to cause the body to lose control. At this time, the role of the AEB is completely opposite to its purpose.
Che Yun's short comment on AEB
Through the AEB experience test on two different technologies, Car Cloud believes that AEB is an integral part of ADAS in the future, and the importance of saving lives is indispensable. However, outside the ADAS system, AEB is inconvenient to impose complete control commands on the vehicle, at least not at present, otherwise it will cause safety hazards due to insufficient information or encountering small probability events.
At the same time, those production cars equipped with AEB must set up a switch that can be manually turned off, and also re-calibrate the sensitivity of AEB for the driving habits and traffic environment of consumers in this market, to avoid too harassing the driver. The problem has happened.
In short, on the road of intelligent car in the future, AEB is our indispensable “same personâ€, but whether it is ADAS or AEB, its core essence is to “recreate†the part of the human brain responsible for driving. Undoubtedly, this road will continue to go a long way.
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