After the "first year of lidar boarding", more and more intelligent electric vehicles begin to carry lidar. However, in the "consensus", there are different voices about the use of lidar.
Recently, Jidu automobile revealed the design details of the front part of the first vehicle Siasun Robot&Automation Co.Ltd(300024) concept car, and the design of headlights and lidar at the front cover are clearly visible. So far, the automatic driving technical scheme of front cover and forward dual lidar of Jidu automobile has been exposed for the first time.
The official of Jidu automobile also said that the design scheme of "dual lidar" is very innovative. The location of lidar is not only distinctive, but also has a very good appearance. Its dual lidar configuration also shows safety advantages.
For this special design, Li Xiang, founder, chairman and CEO of ideal automobile, gave his own view: "there is no difference in performance between one on the roof and two on the hood or bumper. Even the performance of a single one on the top of the head will be better." As soon as these remarks came out, they attracted the attention of the industry. At the same time, Xia Yiping, CEO of Jidu automobile, also had a multi wheel space dialogue with Li Xiang.
multiple lidars or for safety reasons
It is reported that Jidu car adopts at128 of Hesai technology on this concept car, and the full name of the product is "at128 vehicle specification level hybrid solid-state long-range lidar". Coincidentally, the L9 to be released by the ideal car also uses the same lidar, but the number is one and the position is placed on the roof.
Wang Weibao, head of Jidu Zhijia, believes that in addition to the extra points in appearance, the use of two lidars brings more advantages in safety.
Firstly, the point cloud field of view of dual lidar is wider and safer. Compared with the 120 degree FOV (field of view angle) of the single radar scheme, the front dual radar scheme can realize the horizontal 180 degree FOV coverage. In driving scenes such as "ghost probe" and left and right obstructions, the recognition ability of left and right crossing pedestrians or obstacles is stronger.
Secondly, the dual lidar scheme can identify the key areas of vehicles more accurately. In the area of 60 degree FOV in front of the vehicle, the double lidar can double the overlap, more point cloud data on the target and higher recognition accuracy. In terms of redundancy safety of high-order automatic driving, dual lidar can be mutual safety redundancy, which is more reliable than single lidar scheme.
"The 120 degree FOV and 180 degree FOV are still different, and the corner cases solved are also different, so there are differences in product capability, experience and even security." Xia Yiping said.
In theory, carrying more lidars can indeed improve the perception accuracy and safety redundancy to a certain extent, and car companies also began to make an issue on the number of lidars.
Xiaopeng G9, Jihu alpha s, Nezha s, salon machine Jialong, Weima M7, avita 11, Zhiji L7 and other new cars are equipped with two or more lidars. Salon machine Jialong is equipped with as many as four, and shouted the slogan of "don't talk below four" at the 2021 Guangzhou auto show.
"The higher the performance of the lidar, the better, and the more the quantity, the better. Instead, it should be installed in combination with the actual use needs." Gu Jianmin, CTO of Leo China, said publicly, "there are costs behind all sensors, and factors such as system coordination, computing power and power consumption are also involved. Can we use and make good use of so many sensors?"
where is the best place to install in
In addition to the quantity of lidar, its installation position is also the difference between centralized automobile and ideal automobile products. In Li Xiang's view, "it is optimal for pedestrian collision, maintenance cost and vibration control (linking the main vehicle). The only problem is that the shape of the roof lidar will need to be adapted, because it is too much like a mobile soldier - GAODA."
According to the public data, the technical principle of lidar is that the laser transmitter emits a beam of ultrashort laser pulse, the laser is projected onto the target, and the diffuse reflection occurs. Then the laser receiver receives the diffuse reflection light, and calculates the distance from the target to the sensor by measuring the flight time of the laser beam in the air.
Theoretically, it is best to place the lidar behind the windshield, which is like the hidden design of tachograph. However, the windshield is not a completely flat glass, and the transmittance of the windshield under the national standard gb96562016 is not less than 70%, which is not enough to be called high transmittance glass.
This also leads to the fact that if the lidar is placed behind the windshield, it will be like wearing myopia glasses, and the perception will be reduced. Although Apple has also announced the patent of lidar installed on the rear windshield, it is still a long way from mass production, and the cost is ridiculously high.
At present, there are many ways to place lidar in the industry, such as Weilai et7, Weima M7 and ideal L9. The lidar is placed on the roof; For models such as Xiaopeng P5, Xiaopeng G9 and avita 11, the lidar is placed in the central grid or the front fog lamp of the vehicle body; However, the scheme of placing lidar on the engine cover is rare.
In this regard, some analysts said that from the perspective of function and performance, the lidar installed on the roof can be used for sensing and positioning, while the position of the lidar on both sides under the headlights is more suitable for sensing function. Car companies choose where to place the lidar, which is related to vehicle space constraints, cost, power consumption, and the size of the lidar. There are many reasons to weigh.
However, Li Xiang said: "I don't think the lidar will be placed on the hood as shown in the picture when it is mass produced. It should only be placed on the test vehicle. If 2 ~ 3 lidars are used in the front, they will probably be placed on the bumper and wing sector, with better wind resistance and shape, although the cost is higher. At present, the latest pedestrian collision regulations can't pass this position."
It is reported that the Siasun Robot&Automation Co.Ltd(300024) concept car, the first car of Jidu automobile, will be released this year and will be delivered in 2023. Will the installation position of lidar of the car be adjusted and its performance? The industry will continue to pay attention.
