Reporter 丨Sun Lei
A few days ago, Jidu Automobile revealed the design details of the front part of the first car robot concept car, and the design of the headlights and the lidar at the front cover of the car was clearly visible. So far, the front cover and forward dual lidar automatic driving technology scheme of Jidu Automobile have been exposed for the first time.
Jidu Automobile official also said that the "dual lidar" design scheme is very innovative, the location of the lidar is not only distinctive, the appearance is very plus, and the configuration of the dual lidar also shows safety advantages.
For this special design, Li Xiang, founder, chairman and CEO of Ideal Car, gave his own opinion: "Put one on the roof, and put two on the cover or bumper, there is no difference in performance, and even the performance of a single one on the top of the head will be better." As soon as this remark came out, it attracted the attention of the industry, and Xia Yiping, CEO of Jidu Automobile, also conducted multiple rounds of air dialogue with Li Xiang.
Image source: Sina Weibo
1 Multiple lidars or for safety reasons
It is reported that Jidu Automobile uses THE AT128 of Hesai Technology in this concept car, and the full name of the product is "AT128 Vehicle Specification Grade Hybrid Solid-State Long-range LiDAR". Coincidentally, the L9 that Ideal Cars will release also uses the same lidar, but the number is one, and the position is placed on the roof.
Wang Weibao, head of Jidu Intelligent Driving, believes that in addition to the extra points in appearance, the use of two lidars brings more advantages in terms of safety.
First, dual lidar's point cloud field of view is wider and safer. Compared to the 120-degree FOV (Field of View) of the single-radar scheme, the front-end dual-radar scheme achieves a horizontal 180-degree FOV coverage. In driving scenes such as "ghost probes" and left and right obstructions, the ability to recognize pedestrians or obstacles traversing left and right is stronger.
Secondly, the dual lidar scheme is more accurate in identifying the key areas of the vehicle. In the area of 60-degree FOV directly in front of the vehicle, the dual lidar can be doubled and overlapped, and the point cloud data on the target is more, and the recognition accuracy is higher. In terms of redundant safety for high-level autonomous driving, dual lidar can be safely redundant with each other, which is more reliable than single lidar solutions.
Image source: Daily Economic News Infographic
"The 120-degree FOV and the 180-degree FOV are still different, and the Corner Cases (extreme cases) solved are also different, so there is still a difference in the ability and experience of the product and even the safety." Xia Yiping said.
Theoretically, carrying more lidar can indeed improve perception accuracy and increase safety redundancy to a certain extent, and car companies have also begun to make a fuss about the number of lidar.
Xiaopeng G9, Polar Fox Alpha S, Nezha S, Salon Mecha Dragon, WM M7, Avita 11, Zhiji L7 and many other new cars are equipped with two or more lidar, Salon Mecha Dragon is equipped with as many as four, and shouted the slogan of "don't talk below 4" at the 2021 Guangzhou Auto Show.
"Lidar is not the higher the performance, the better, nor the more the better, but should be combined with the actual use of the needs of the installation." Gu Jianmin, CTO of Leo China, said publicly, "There is a cost behind all sensors, and it also involves factors such as system coordination, computing power and power consumption. ”
2 Where is the best location to install?
In addition to the number of lidar, its installation location is also the difference between jidu automobile and ideal automobile products. In Li Xiang's view: "In pedestrian collisions, maintenance costs, and vibration control (linking the main car), (placing lidar on) the roof is optimal. The only problem is that the shape of the roof lidar will need to be adapted, because it is too much like a mobile suit - Gundam. ”
Public information shows that the technical principle of lidar is that a ultra-short laser pulse is emitted by the laser emitter, the laser is projected onto the target, diffuse reflection occurs, and then the diffuse reflected light is received by the laser receiver, and the distance from the target object to the sensor is calculated by measuring the flight time of the laser beam in the air.
Theoretically, lidar is best placed behind the front windshield, like a dashcam. However, the windshield is not a completely flat glass, and the light transmittance of the windshield under the national standard GB9656-2016 is only not less than 70%, which is not enough to be called high transmittance glass.
This also leads to the fact that if lidar is placed behind the windshield, it is like wearing myopic glasses, and the perception ability will be reduced. Although Apple has also announced a patent for lidar installed on the rear windshield, it is still a long way from mass production, and the cost is also ridiculously high.
At present, there are a variety of lidar placement methods in the industry, such as Weilai ET7, WM M7, and Ideal L9 to place lidar on the roof; Xiaopeng P5, Xiaopeng G9, Avita 11 and other models place lidar in the middle net or front fog light position in front of the body; and the scheme of placing lidar on the engine cover used by Jidu Automobile is relatively rare.
Image source: Daily Economic News Zhu Xingyun photo (data map)
In this regard, some analysts said that from the perspective of function and performance, the lidar installed on the roof can be both perception and positioning, and the position of the lidar on both sides under the headlights is more suitable for the perception function. The choice of where to place lidar is related to factors such as vehicle space limitations, cost, power consumption, and the size of lidar, and there are multiple reasons to weigh.
However, Li wanted to say: "I think that when [Jidu Automobile] is mass-produced, the lidar will not be placed in the position of the cover shown in the picture, it should only be the placement of the test vehicle." If 2 to 3 lidar are used in the front, there is a high probability that it will be placed on the bumper and fender, and the wind resistance and shape will be better, although the cost is higher. At this current position, the latest pedestrian collision regulations cannot be passed. ”
It is reported that Jidu Automobile's first automotive robot concept car will be released this year and delivered in 2023, when the lidar installation position of the car will be adjusted, and how will its performance be? The industry will continue to pay attention.
Cover image source: Visual China