No braking, direct rear-end collision?Q: Why doesn't the AEB of the M7 work?

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2024-04-29 10:29Posted in Beijing Automotive Creators

On April 26, a Wenjie M7 in Yuncheng, Shanxi Province had a rear-end collision and caught fire after hitting a maintenance vehicle.

The video posted by netizens shows that the front engine room of the M7 rear-end maintenance vehicle caught fire, thick smoke billowed and the open flames were very high.

As a result of the accident, all three people in the car were killed. According to the family members of the deceased, the three people in the car were her husband, brother and her own son.

The information completed by netizens shows that this Wenjie M7 has only been bought for 3 months, although it is not clear about the configuration, but it is determined to have AEB function.

Wenjie responded at the first time and gave some key information: the speed of the vehicle was 115km/h at the time of the accident, the airbag was deployed normally, and the battery pack characteristics were normal.

The family raised their own questions about the incident, including a paragraph about AEB, which reads:

"The new car Huawei M7, which is only 3 months old, is advertised as AEB automatic emergency braking and GAEB special-shaped obstacle automatic emergency braking..... But where do these functions come into play when an accident happens?"

At the time of the accident, did AEB work at all? or did it work but failed to fully stop it? Since there has been no official response to AEB's question, we cannot fully confirm what the specific situation is.

But as a technical controller, today you might as well do some analysis and popular science from a technical perspective according to the known situation.

What is the AEB level of Q M7?

Through the press conference and a lot of online publicity, it is generally believed that the AEB capability of the M7 is very high: for example, the maximum braking speed is 90km/h, and the capacity is increased by 50%.

However, it should be noted that these are for the "high-end AEB" with ADS2.0 technology, that is, only on the intelligent driving version of the model.

And the accident vehicle, according to the owner's description, should be a low-profile version of about 250,000. As can be seen from the official configuration table, the M7 low-end model does not have ADS 2.0. There is no lidar on the hardware, and the number of high-definition cameras is relatively small.

Some netizens said that the low-profile M7 that had the accident used Bosch's AEB solution, but Bosch has officially refuted the rumors and denied this statement.

No matter which vendor's solution is used, but in short, the current industry's conventional AEB capabilities are relatively basic. For example, the maximum working speed range is about 60km/h, and the ability to recognize obstacles is limited.

What is the difference between AEB and higher-order AEB?

The first step in the working principle of AEB is to "see" the object in front of you. It also relies on hardware such as cameras and radars to complete perception.

The second step is to "identify and judge". If the object in front of you is an obstacle that affects safety, then you need to slow down and brake, and if it is an object such as a plastic bag, leaves, etc., you should not brake. Otherwise, the AEB will be triggered by mistake frequently, which will affect driving safety.

The third step is to "execute". Including braking strength, timing, warning information, etc., all need to respond in time according to different situations.

The main difference between conventional AEB and higher-order AEB is that in the first two steps, it can even be said that there is a world of difference.

As mentioned earlier, the low-profile version of the M7 has no lidar, and the number of high-definition cameras is not much, and the computing platform is not ADS2.0. Then when encountering a special-shaped object, or the speed of the vehicle is too high, it will affect the two steps of "seeing" and "recognition".

So back to this accident, the highway is not less than 115km/h, and there is a "special-shaped" sprinkler truck in front, and it is naturally impossible for conventional AEB to make a timely and correct judgment.

What are the capabilities of higher-order AEBs?

The GAEB of the high-end version of the M7 is based on the traditional AEB and strengthened by the "GOD General Obstacle Detection Network" technology in the ADS 2.0 intelligent driving solution, and the latter has two advantages:

Stronger obstacle recognition

The entry-level version of the M7 AEB is very conservative in terms of intelligence, such as perceiving, identifying obstacles, the algorithm model used is very primitive, and the various obstacle data required to add the "white list" is also very small.

ADS 2.0, which GAEB is backed by, has already embarked on the data-driven route of "big data + large model", so its "white list" can quickly and accurately identify more types of obstacles.

In addition, based on the type of obstacle and its current driving trajectory, GOD can also predict their next behavior, and then actively control GAEB to slow down in advance.

Activates at higher speeds

When starting ADS 2.0 at high speeds, it tends to set a maximum cruise speed and slow down until it comes to a stop when encountering a slow vehicle or stationary obstacle in front of you.

The GAEB can reach an activable speed of up to 150km/h, in fact, the principle is similar to this, in essence, it is to identify distant obstacles farther and faster, first slow down the vehicle to a safer speed range (such as the industry's default 60km/h), and then AEB brakes.

Can we trust higher-order AEB?

However, "high-level AEB" should not be blindly trusted, because in principle, AEB only helps drivers reduce accident losses in low-speed scenarios, and its original intention is not to be absolutely safe.

Secondly, the premise of the reliability of "high-end AEB" is that all perception hardware can work normally, and components such as cameras and lidars are easily blocked and defaced due to weather and other reasons.

Finally, the AI backed by "high-order AEB" is actually not completely reliable, because the deep neural network that constitutes the intelligent driving AI framework has black-box properties, which leads to uncertainty in its output results.

In other words, even in the face of the same rear-end collision scenario, the M7 equipped with high-end AEB may come up with a variety of different evasion strategies, and may even directly collide with a rear-end collision.

However, this question alone is enough to expand on another article, so let's stop here.

Personal opinion

In general, AEB, as an active safety technology, can help drivers improve the fault tolerance rate at medium and low speeds, but it cannot guarantee absolute safety, and the main body of safety is still the driver himself.

In addition to the drivers themselves, car companies also have unshirkable responsibilities, such as the habit of confusing and fuzzy concepts when doing product marketing in the early stage, using the parameters of the top models to refer to all configuration models, and then using the small words hidden in the corners to clear the responsibility, which will also mislead consumers' cognition, which will inadvertently bury a lot of possible accidents.

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