Tencent Technology News On the evening of April 22, there was new progress in the rights protection of female car owners at the Shanghai Auto Show. Tesla disclosed through the media some of the core data of the vehicle within 30 minutes before the accident.
The data shows that when the driver stepped on the brake pedal for the last time, the vehicle speed was 118.5 kilometers per hour. Within 2.7 seconds after the driver stepped on the brake pedal, the maximum brake master cylinder pressure was only 45.9 bar. After that, the driver increased the stepping on the brake pedal, and the brake master cylinder pressure reached 92.7 bar. The front collision warning and automatic emergency braking function were activated (the maximum brake master cylinder pressure reached 140.7bar) and played a role, reducing the amplitude of the collision. 1.8 seconds after the ABS was applied, the system recorded the occurrence of the collision. After the driver stepped on the brake pedal, the vehicle speed continued to decrease, and before the collision, the vehicle speed was reduced to 48.5 kilometers per hour.
In summary, the vehicle is running at a higher speed, and the driver starts to depress the brake pedal with a lighter force. After that, the automatic emergency braking function is activated and has a function, which improves the braking force and reduces the impact of the collision. The driving system is normally involved in the work and reduces the speed of the car. According to data released by Tesla, Tencent Technology is authorized to sort out the opinions of users.
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Opinion 1: Tesla has a situation where it selectively releases data that is beneficial to its own side The data disclosed by Tesla through the media is incomplete and cannot give a clear conclusion on the cause of the accident. Tesla has more detailed and richer data, but it has not announced it. There is a suspicion that selective publication of the published data is beneficial to oneself. Zhihu user Shi Gaoba believes that data such as the data of the brake pedal depth sensor is selectively not released by Tesla. The braking process requires the participation of multiple systems, including at least the brake pedal switch sensor, pedal depth sensor, motor, vehicle controller, ESP system (including ABS), the activation of AEB emergency braking, and the participation of forward radar. As a result, only a few seemingly professional data such as vehicle speed, pedal switch signal, and brake cylinder pressure were given. The pedal depth data, motor speed signal, and forward radar data are all given to completely restore the process of the car owner’s braking, motor speed and vehicle speed verification, and forward radar to see the distance of the vehicle ahead. The data of the brake pedal depth sensor can truly reflect whether the owner has stepped on the pedal violently, and whether the pedal cannot be stepped on due to the increased resistance of the pedal. Tesla said that the driver stepped on the brake pedal, but did not release the data. Zhihu user Mr. He said that Tesla has more abundant data, but Tesla has not disclosed it publicly. Currently, only Tesla is equipped with an EDR (Event Data Recorder) data recorder, which can be understood as a black box. The measurement frequency of the data recorded by the black box EDR is currently unknown, only Tesla employees. But the amount of data measured is definitely detailed, borrow a picture: As can be seen from this figure, the key information recorded by Tesla’s EDR is: Vehicle speed; odometer; camera data, braking and acceleration data, short video clips of accidents, safety system data, etc. If you want to analyze what happened when the accident happened, I think some key information is needed: Collision sensor signal: can know the time of the collision Brake signal: It is not only necessary to know whether the brake is pressed, but also to know the stroke of the brake pedal (how much the brake is pressed). Brake cylinder pressure signal: can know whether the brake cylinder provides boost Accelerator pedal signal: Including the degree of opening, you can know if the accelerator was stepped on before and after the accident Speed signal: can know the current speed ABS/esp signal: can know whether ABS is activated and whether esp is activated or not Motor status: including motor speed, quadrant, motor torque, etc., to see if the motor is still providing driving force when the brake is stepped on. ibooster status: able to know the distribution of braking torque. Vehicle failure information: whether there is a failure Note that the above data requires raw sensor data. Taking the brake pedal as an example, in addition to knowing the final opening signal, you also need to know the most original voltage signal. The voltage signal is the true sensor value. Viewpoint 2: Sufficient braking measures have been given According to Tesla, the vehicle is traveling at a higher speed, and the driver starts to depress the brake pedal lightly. After that, the automatic emergency braking function is activated and works, increasing the braking force and reducing the impact of the collision. , The braking system is normally involved in the work and reduces the speed of the car. Zhihu users questioned this statement, believing that the driver depresses the brake pedal in 23.17 seconds and triggers abs in 25.74 seconds, and sufficient braking measures have been taken. The following are the views of Zhihu user Kang Jianmao: It can be seen from the data that the driver depresses the brake pedal from 23.17 seconds, the pressure of the master cylinder gradually increases, and then triggers abs at 25.74 seconds (at this time aeb does not start, indicating that the driver has already done so without the help of aeb The maximum deceleration capacity of the vehicle was reached by stepping on the brakes), and then the pressure of the master cylinder continued to rise, until it reached the peak value in 27.63 seconds (maybe aeb, or it may be a miracle of the owner’s life and death). However, Tesla’s own text stated that within 2.7 seconds of stepping on the brake, the pressure of the master brake cylinder was only 45.9 bar. Please, did you step on the abs at that time? What does it mean? How many people can step on abs when driving? Then Tesla himself said that the brake pressure gradually increased to more than 90 afterwards. Anyone who knows a car knows that once the ABS is started, it has basically reached the maximum braking capacity of the vehicle, and then it will not work if it is stepped on. Tesla also said that aeb played a role and successfully helped slow down, excuse me? This wave of data actually proved that the driver stepped on the brake hard enough. After all, it was the abs that was stepped on by others. Then even if the aeb system intervened, it did not help to decelerate. If you can’t stop it, you can’t stop it. Viewpoint 3: Deceleration is 0.6g, the braking ability given by Tesla cars is not enough Under normal circumstances, the braking of a family car is 1g, but Tesla’s ABS trigger condition is only 0.6g, which is lower than that of a normal family car. The following are the views of Zhihu user Kang Jianmao: According to the data given by Tesla itself, from a speed of 94 in 25.41 seconds to a speed of 48.5 in 27.45 seconds, the vehicle speed dropped by 45.5 kilometers per hour when the ABS was triggered in 2 seconds (that is, full braking). The total is 12.63 meters per second, and the average acceleration is 6.3 meters per second. This braking ability really proves that Tesla can’t stop. The ABS is only about 0.63g, and the normal family car is close to 1g. The following are the views of Zhihu user cao sir: Dare the driver lightly step on the brake to trigger ABS, but hardly stepping on the brake is not enough to trigger ABS. Is this logical?
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