Lidar knowledge drops

Laser radar lidar Knowledge
LiDAR（Light Detection and Ranging）, It is the abbreviation of laser detection and ranging system , Also known as Laser Radar [1] or LADAR（Laser Detection and Ranging）.
Use the laser as the emission light source , Active remote sensing equipment using photoelectric detection technology . Lidar is an advanced detection method combining laser technology and modern photoelectric detection technology . By the launch system 、 Receiving system 、 Information processing and other parts . The emission system is various forms of lasers , Such as carbon dioxide laser 、 Neodymium doped yttrium aluminum garnet laser 、 It is composed of semiconductor laser, wavelength tunable solid-state laser and optical beam expanding unit ; The receiving system adopts telescopes and various forms of photodetectors , Such as photomultiplier tube 、 Semiconductor photodiode 、 Avalanche photodiodes 、 Combination of infrared and visible multi detector devices . Lidar adopts pulse or continuous wave 2 Ways of working , Detection methods can be divided into meter scattering according to different detection principles 、 Rayleigh scattering 、 Raman scattering 、 Brillouin scattering 、 fluorescence 、 Doppler lidar .
Laser radar （ english ：Laser Radar）, It detects the position of the target by emitting a laser beam 、 Radar system with velocity and other characteristics . Its working principle is to send detection signals to the target （ laser beams ）, Then the received signal is reflected back from the target （ Target echo ） Compare with the transmitted signal , After proper treatment , You can get information about the goal , Such as target distance 、 bearing 、 Height 、 Speed 、 Posture 、 Even shape and other parameters , Thus to the aircraft 、 Detect targets such as missiles 、 Tracking and identification . It consists of a laser transmitter 、 Optical receiver 、 Turntable and information processing system , The laser converts electrical pulses into optical pulses and emits them , The optical receiver then restores the light pulse reflected from the target into an electrical pulse , To the display .
References to this article are linked to
https://baike.baidu.com/item/%E6%BF%80%E5%85%89%E9%9B%B7%E8%BE%BE/2374379?fr=aladdin
https://mp.weixin.qq.com/s/ysETJJiUDSv2VwJti8A6pA
https://mp.weixin.qq.com/s/m8ClcPulVogEGSUiKGrzug
https://maimai.cn/article/detail?fid=1727536333&efid=ytv0cEz1AFwodMFz5iwTzQ&share_channel=2&webid=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ1IjoyMjgyMzM0MzMsImZpZCI6MTcyNzUzNjMzM30.Fex0xrlsL5RMokoneoefZnpaiLYKjEdjEBC9onZWtaY&use_rn=1&_share_channel=wechat
Where should the laser radar be installed ？

The intensive dual lidar scheme has aroused heated discussion . that , Where should the laser radar be installed ？ What are the effects of different positions on its performance ？

Once the dual lidar scheme of the integrated automotive robot is announced , It triggered a heated debate .
Where should the laser radar be installed ？ This seems to be a trivial problem for everyone , Li Xiang 、 He Xiaopeng and Jidu CEO Xia Yiping expressed his opinions one after another . Before concentration , Most on-board lidars are installed on the roof or front bumper . Installing two retractable lidars on the front cover of the car can be said to be a very groundbreaking scheme .
And considering the practicality , How about this plan ？
01 Ideal and set degree scheme
The description of its dual lidar scheme is ： Not only distinctive , The appearance is very good , The configuration of dual laser radar also shows security advantages . First , The point cloud field of view of dual lidar is wider 、 More secure , Compared with the single radar design 120 degree FOV, The dual radar at the front of the vehicle can realize horizontal 180 Degree FOV Cover . stay “ Ghost probe ”、 There are obstructions on the left and right in driving scenes , The ability to recognize pedestrians or obstacles crossing left and right is stronger . secondly , The identification of key areas of vehicles is more accurate , Right in front of the vehicle 60 degree FOV In the area , Double lidar overlap , More point cloud data on the target , Higher recognition accuracy . Third , In terms of redundant safety of high-order automatic driving , Dual lidar can be mutually safe and redundant , It is more reliable than the single lidar scheme . Li Xiang commented almost immediately ： “ Put a... On the roof , And put two on the cover or bumper , There is no difference in performance , Even a single one on the top of the head will perform better . however , In pedestrian collisions 、 Maintenance cost and vibration control （ Link main body ） On , The roof is the best . The only problem is , The shape of the roof lidar will need to adapt to , Because it's too much like a mobile warrior - Up to .” Of course , Li wants his own ideal L9 Is the roof lidar scheme used .

the second day , Xia Yiping also responded immediately ： “ There is still a difference ,120 Degree FOV and 180 Degree FOV It's not the same , Solved corner case Are not the same as , Therefore, there are differences in product capability, experience and even security .” For these advantages , Li Xiang is probably also recognized . But at the same time, he also believes that , The lidar should not be placed on the front cover during mass production , Because I can't pass the latest Pedestrian Collision Regulations . According to Zhang Jiahao, head of Jidu marketing growth, at the media communication meeting , The currently announced lidar scheme is to install two lidars symmetrically on the front cover of the vehicle , Liftable , It can shrink when not in use . This is the solution of the integrated concept car . The possibility of changing the installation mode during subsequent mass production is not ruled out .
02 The influence of different installation positions on the covering surface
Is it better to put two on the front cover or one on the roof ？
For now , The two schemes have their own advantages and disadvantages .
Zhijia.com consulted Liangdao intelligent, a mass production solution supplier of lidar system , Tested a variety of different routes of lidar at home and abroad , And have a deep understanding of the mass production of lidar . Liangdao intelligence thinks , Different mounting heights are different for target detection , The higher the elevation, the greater the blind area of the surface line . But at the same time , The vision will be better , You can cross the car in front and detect the car in front . The angle of view needs to be considered when installing the roof （FOV） Position of the lower edge heel top cover , Therefore, according to different models, there is usually a few degrees down adaptation . If installed on the hood , Generally, the hood is relatively flat , You need the lidar to tilt up , Sacrifice part of the lidar FOV. The main influence here is the vertical of lidar FOV. Generally vertical FOV smaller , With ideal and intensive use of Hesai AT128 For example , level FOV Perpendicular to FOV Respectively 120 Degree and 25.4 degree . Because the mechanical lidar adopts the rotating mirror mode , level FOV Can be up to 360 degree . But for the time being, only vertical FOV. Zhijiajun borrowed a legend from Suteng juchuang to show the impact of lidar installed in different positions on vertical field of vision . It can be seen that , In the vertical field of view , The higher the lidar is installed , The farther the field of vision , But the blind area nearby will be relatively large . thus , In terms of coverage , If the scheme is to install a forward lidar on the roof , Add... At the four corners of the vehicle 2-4 Among them, short and medium range lidar is a safer way . This is also a reasonable configuration considered by Liangdao intelligence . Of course , It depends on the needs of car enterprises to install lidar . On the premise of cost performance , If we pay more attention to the identification of nearby obstacles , Choosing to install lidar at a lower position can minimize the blind area in the vicinity . If Mercedes Benz has L3 Level of automatic driving assistance EQS. Because of the L3 Level 1 automatic driving capability is in high-speed congestion , The vehicle speed is less than 60km/h Automatic driving when , The second generation of Valeo SCALA The purpose can be achieved by installing the lidar in the middle of the front bumper .

However, when the installation position is low, the problem that it is easy to be blocked by the front should also be considered , It requires the cooperation of other sensors .

The scheme that the concentration is installed on the front cover of the vehicle belongs to a relatively central position . When using AT128 Lidar itself has 10% Under reflectivity 200 Under the premise of M detection distance , You can get a moderate view . If it is in a high-speed scene , Generally, there are few obstacles nearby , Roof lidar can have a better view of the distance . Those who adopt this scheme include Wei Lai ET7, Including ideal L9. Of course , Local tyrant's words , Full coverage of nature is the best . The advantages of the integrated dual lidar scheme are mainly reflected in the level FOV On . First , At present, the lidar of mass-produced vehicles is basically semi-solid , Can't reach the mechanical 360 Degree level FOV. As for why not use mechanical , On the one hand, it's expensive , On the one hand, it's ugly . Ideal L9 And Hesai used by Jidu AT128 Lidar level FOV by 120 degree . here , The advantage of using two lidars is obvious . At the level FOV On , A single lidar can only achieve 120 Degree of coverage , Two can be achieved 180 Degree of coverage . Straight ahead 60 Within the overlapping area of degrees , Due to the high density of point clouds , Recognition ability is also stronger , Higher accuracy .

Of course , What is discussed here is only when all other variables are the same , Simply consider installing in different positions to FOV Influence . In terms of actual effect , Naturally, it is also affected by the performance of lidar itself . On the level FOV, Xiao Peng said that he had considered installing two lidars on the roof .“ At first, I wanted to put two on the roof , But design anyway , Are similar to the harrow ears of Rabbits , I gave up later .”
03 appearance 、 The impact of the project, etc
It involves other considerations when selecting the installation location , For example, appearance . Li Xiang said that the only problem with installing it on the roof is that it looks too much like a Gundam soldier , Need to adapt .

Have to say , Ideal L9 The shape of lidar on the roof is really a little unspeakable , Wei Lai's handling is quite pleasing to the eye .
But no matter how designed , If the lidar is installed on the roof, there will be an extra bulge . This not only affects the appearance , At the same time, it will also have an impact on the wind resistance performance of the car .

Finally, Xiao Peng chose to install it in the headlights on both sides , Do concealment .

Like Audi, which was first equipped with lidar A8 And Mercedes EQS, Lidar hardware is also integrated on the bumper , It has little effect on the appearance . Besides , Many details such as engineering problems need to be considered when selecting the installation location . for example , Liangdao intelligence believes that from an engineering point of view , The lidar is mounted on the roof , Mud thrown 、 The impact of gravel impact is also relatively small . But installed on the roof , It is difficult to control the use of the cleaning device . In addition, the roof may be too hot in summer due to sun exposure , It will also increase the speed of product aging . The main challenge of pop-up installation scheme is the reliability of engineering . for instance , Due to mechanical aging during use , Deviation of installation angle caused by vibration and other reasons , The requirements for on-line dislocation detection and correction are high . As Li wants to put forward , Put the lidar on the front cover , There are hidden dangers in pedestrian protection , Unable to pass the latest Pedestrian Collision Regulations . At present, the front covers of cars on the market are generally designed to be softer , Be flexible , In order to minimize the injury when colliding with pedestrians , However, the installation of lidar obviously can not meet this requirement . meanwhile , The position of the front cover is also easy to deform in daily small collisions , The lidar is easily damaged , Thus pushing up the maintenance cost of minor accidents . Where is the lidar , It's not a single line thinking problem , Consider the perception performance 、 Security 、 cost 、 Balance and trade-offs after various factors such as appearance and Engineering .
04 Multi lidar scheme
If you don't consider the cost , A forward long-range lidar is installed on the roof , Body installation 2-4 Medium and short range angle lidar is a reasonable and safe scheme . Check several schemes that are not bad for money .
Goodway M7 carrying 3 Two lidars , Located on both sides of the roof and fender respectively , It is from Suteng juchuang M1, The horizontal detection range is up to 330 degree .

Make a high-profile claim “4 Don't talk below the stars ” My salon car , More for “ Mecha Dragon ” Configured with 4 Two lidars . Mechatron adopts Huawei 96 Line lidar , From the official website ,4 The positions of the two should be one on the roof , One on each side of the front , And one at the back of the car .

Same use 4 There are also three lidar schemes 3 Lutes released in June ELETRE, carrying 4 Satellite radar , There are two retractable 128 Line lidar , Also from Hesai . The layout adopts two front wheel eyebrows , One on the front and one on the back of the roof .

The multi lidar scheme basically adopts the above-mentioned scheme of roof forward lidar plus surrounding blinding , It should be said that the security at the sensing end is worthy of affirmation .
Of course , Considering the cost of lidar , These cars are not cheap .
05 Conclusion
2022 It is called the first year of lidar . The so-called first year , That is, there is no previous experience to refer to . In the process of mass production of lidar , What kind of effect to achieve , What kind of technical route to adopt , With a few lidars , How to install , Are still exploring . Just as there is no final conclusion on what technical route of lidar is better , There is no final conclusion about where to install it , It needs to be determined according to the different needs of the main engine factory . The bright track indicates , The mass production of lidar is a long process , There is still a long way to go from hardware landing to mass production and boarding . In cooperation with foreign main engine manufacturers, when the laser radar is put into mass production , The other party will provide several thick materials , The project requirements are listed in detail . The consideration of installation location is only a tiny part . The domestic main engine factory has not yet formed such a standard . What technology does each company use , How to install is still in the state of letting a hundred flowers bloom . There are many possibilities for the mass production of laser radar .
Equipped by lutes 4 Two lidars , Hesai , Suteng juchuang will make another city
2022 year 3 month 30 Daily news , Lutes at London time 3 month 29 Japan 19:30（ Beijing time. 3 month 30 Japan 2:30） Officially released its first pure electric SUV models ——ELETRE, The new car is expected to be officially put into operation in Wuhan intelligent factory in the second half of this year ,2023 In China 、 Listed in the UK and European markets .
The second type of carrying 4 Lidar models
It is reported that Eletre Carrying 4 Two lidars , This is the first after the Great Wall mecha dragon 2 With 4 A lidar model , Let's introduce the driving aid sensor of this model .
Lotus Eletre In addition to carrying 2 NVIDIA Orin chip ,Eletre Carrying 34 A driving aid sensor ：
• 4 Two lidars
• 6 Millimeter wave radar
• 12 An ultrasonic radar
• 4 star 200 Wanhuan camera
• 7 star 800 Wan auxiliary driving camera
• 1 An interior camera
in addition ,Eletre Also carry the 2 High pass 8155 chip , Support super image rendering 、 Support 3D Image and other functions .

It is reported that , Lotus Eletre The lidar is located on the top of the windscreen , And the front wheel arches on both sides , It is a telescopic lidar , Fit roof curve 、 Hidden door handle, etc , Not only makes the shape of the whole vehicle very beautiful , Ensure ultra-low wind resistance coefficient .

About lidar suppliers
Infer from the position of the lidar in the video , The lidar located on the top of the front windshield is mainly used to realize ADAS Ranging function , It belongs to long-range lidar . The lidar located on both sides of the front wheel should be a short-range lidar .
Eletre Forward lidar AT128
It is understood that the supplier of long-range lidar is Hesai technology , Probably using Hesai Technology AT128, at present , Hesai AT128 It has obtained more than millions of OEM front assembly and mass production points all over the world , Including ideal 、 Set degree 、 Gao He 、 Lutes et al .

AT128 Core indicators

AT128 Image level point cloud display

AT128 With other typical hybrid solid-state lidar detection 200 Meter object contrast time

AT128 Measured point cloud shows HD perception
It is understood that the supplier of blinding lidar is Suteng juchuang , The probability is that Suteng juchuang M1, Except lutes , Rapid M1 At present, it is also the only vehicle mounted solid-state intelligent lidar in the world , It has won the global 40+ The model is fixed . Including SAIC Zhiji 、 GAC AIAN 、 BYD 、 Polar krypton 、 Xiao peng 、Lucid etc. , Besides passenger cars, there are also commercial vehicles , Such as FAW Jiefang .

According to the official introduction ,M1 Through a series of patented technologies , It can ensure the safety and reliability of point cloud data quality in various driving scenes , Eliminate thorny problems in the industry from the product side . Besides ,M1 There is also built-in stain detection 、 Intelligent cleaning 、 Intelligent heating 、 Performance test 、 Power management 、 Network management and other supporting functions , achieve ASIL-B Functional safety level , To help the vehicle sensing system achieve ASIL-D Functional safety design .

In addition to grinding high performance 、 Vehicle specification level hardware , Sagitar also has unique software and hardware innovation ——MEMS Two dimensional scanning chip technology endows M1 Intelligent zoom 「 gaze 」 function , in other words M1 The transverse and longitudinal scanning speeds can be changed arbitrarily to change the scanning shape , And the switching can be completed in the next frame after receiving the instruction . This function is similar to the zoom technology of the camera , The scanning mode can be adjusted according to the driving scene , Always focus on the key perception areas concerned by the driver , Improve lidar perception , Help enhance autopilot performance .

Integrated automatic driving , Pure vision and lidar
4 month 18 Japan , Jidu once again disclosed the appearance of a small part of its first concept model , This time, the focus is on the design of headlights and lidar at the front cover , The boarding of lidar means that Jidu has finalized the hardware system of automatic driving scheme .
Jidu's first car robot concept car front cover （ Graph self concentration ）
Wang Weibao, head of Jidu Zhijia, said , Set degree SIMUCar（ Software integration simulation sample vehicle ,Software Integration Mule Car） The iteration is upgraded to 2.0 edition , Its auto drive system has been added to lidar sensor. , And with the self-developed high-order automatic driving intelligent architecture JET1.0（ Electronic and electrical architecture +SOA） Achieve convergence .
According to Wang Weibao ,SIMUCar 2.0 At this stage, the pure vision and lidar autopilot schemes are being tested and developed , It can be independent of each other in algorithm , The purpose is to realize the redundancy of mass production vehicles in perceived safety . Compared with the traditional scheme , The two automatic driving schemes are backup to each other 、 Complement each other , Both self driving and cooperative .
Supply chain , The choice of integration is NVIDIA autopilot chip Orin X Hesai technology semi-solid state lidar AT128.
Two lidars are used for the concentration , Compared with more lidar schemes, it has certain cost advantages , Compared with the single lidar scheme 120 degree FOV（ Field angle ）, Can achieve level 180 Degree FOV Cover , So as to strengthen the automobile in “ Ghost probe ”、 Recognition ability in driving scenes with obstructions on the left and right . Besides , The scheme can be directly in front of the vehicle 60 degree FOV Double the overlap in the area , This is also the area where the vehicle needs to be identified .
For the selection of lidar scheme , Wang Weibao told the interface news , Jidu has studied and judged many schemes such as semi-solid or pure solid , But as a mass production model , The first consideration is the mass production cycle .
“ So the production capacity of lidar , Performance indicators , such as FOV、 Perceptual blind spot 、 Overall dimensions 、 Price, etc , Whole （ choice ） Based on the so-called entrepreneurial period .” Wang Weibao said ,“ It's more about defining hardware through software , Consider what is needed to implement the software solution .”
meanwhile , Wang Weibao said , Based on the prediction of the future development of sensor technology , Concentration will make a set of schemes that pure vision and lidar are independent of each other .“ From a perspective , With the gradual improvement of the algorithm in the next stage , The performance of sensors may move towards more extensive scenes .” As a car company , It is hoped that a single sensor has wider scene recognition ability .
SIMUCar It is used in the development process of front autopilot function and digital intelligent cockpit 、 R & D process to improve mass production efficiency . According to introducing ,SIMUCar 1.0 It was last year 12 The high-speed project will be completed in June 、 Urban dual domain integration , And this year 2 At the end of this month, we completed the integration and intelligent architecture JET1.0 Fusion adaptation of .
Wang Weibao said ,SIMUCar1.0 and 2.0 It's the relationship between primary school and middle school .SIMUCar1.0 This stage focuses more on the basic capacity-building of automatic driving , Including the development of software architecture and related basic functional logic , And adapt to the chassis ;SIMUCar 2.0 It is a time to improve and form basic capabilities , Its underlying architecture has been upgraded to a self-developed high-level automatic driving intelligent architecture JET（JIDU Evolving Technology）, Including electronic and electrical architecture EEA And vehicle operating system SOA.
stay SIMUCar 2.0 Stage , Related domain controllers and sensors , It has gradually reached the state of mass production , Some basic autonomous driving ability , Include ADAS function , Parking , Intelligent interaction, etc , Will gradually reach the state of mass production .
However, the research and development method of software and hardware decoupling , It will also cause doubts about the final software and hardware adaptability of Jidu automobile .
Regarding this , Wang Weibao explained that , The core of this problem is what the team does JET, The latter provides almost all the electronic and electrical architecture of the whole vehicle involved in intellectualization , Including core domain control 、 Sensors and their paths, etc , This can ensure that the vehicle completes the software and hardware decoupling development .
“ At the end of this year , The real vehicle is used for joint debugging .” But because of 95% even to the extent that 98% The software development function of has been based on JET Development complete , The proportion of joint commissioning will be very small .

Reference link
https://baike.baidu.com/item/%E6%BF%80%E5%85%89%E9%9B%B7%E8%BE%BE/2374379?fr=aladdin
https://mp.weixin.qq.com/s/ysETJJiUDSv2VwJti8A6pA
https://mp.weixin.qq.com/s/m8ClcPulVogEGSUiKGrzug
https://maimai.cn/article/detail?fid=1727536333&efid=ytv0cEz1AFwodMFz5iwTzQ&share_channel=2&webid=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ1IjoyMjgyMzM0MzMsImZpZCI6MTcyNzUzNjMzM30.Fex0xrlsL5RMokoneoefZnpaiLYKjEdjEBC9onZWtaY&use_rn=1&_share_channel=wechat