Shanghai Auto Show is here.
This year, Many car brands such as Xiaopeng, Yulai, Extreme Fox, R-car will bring automatic driving lots of laser radar.
On the automatic driving, China Car Enterprise is a collective of Tesla’s opposite.
Tesla believes that pure visual can be fully automatically driven.
Today’s mainstream Chinese car enterprise, start the automatic driving plan of laser radar.
Why is the laser radar is a sensor for L3 intelligent driving?
The automatic driving perceptual task is to build an accurate 3D environment model in real time.
Depth learning plus single, three visual vision is unable to complete this task.
The fatal defect of single-graph / three-go camera is that such systems must first identify information that can detect the target, target recognition (classification) and detection (Detection) are unable to split.
The cognitive scope of the depth learning algorithm is derived from the breadth and richness of the data set, and the data set is always limited, so the depth learning algorithm will definitely have missed inspection.
If the target cannot be identified, the system will think that there is no obstacle in front. Most of the travelers have been this reason.
The above, that is, the single / three purpose system missed inspection cannot be avoided, so it can only use the system of L2.
L2 or more, there must be laser radar, and laser radar will bring an overwhelming security advantage.
In a sense, the role of laser radar vendors can be considered system integrators.
Traditional laser industries can provide ripe zero components including laser emissions and receiving portions, and these zero components in the industry have more than 15 years of technical precipitation, like a 1550 nm laser receiving diode.
Laser radar companies are not more than 3 years in the laser diode field, so their main work is to design scanners.
Scanners can also purchase ready-made products.
Such as Japanese NIDEC’s polygon scanner, Mirror’s MEMS spray mirror.
To a certain extent, the threshold of R & D laser radar products is not so high.
Laser radar manufacturers want to master core technology, it is self-developed self-produced scanner.
1. Ideal and reality collision: the best solution for the current laser radar mass production
The ideal laser radar technology is non-Flash.
Regardless of performance, ecology, cost, volume, and car rules, Flash laser radar is almost perfect.
However, the bottleneck of Flash laser radar is currently too poor, which is mainly the laser transmitting end of Flash laser radar is a VCSEL array.
The power density of the VCSEL array is far from the traditional laser diode ratio. Once the bottleneck is broken, the Flash laser radar can sweep the market.
However, in the current perspective, Flash Laser Radar To achieve a mass production breakthrough at least 5 years.
Another technology route is a silicon-optoelectronic FMCW laser radar, and the technical maturity is also lower than Flash, and even if the technology matures, the price is higher than the Flash laser radar.
The FMCW laser radar requires expensive femtosecond laser generators, and the tuner works in the terahertz band, even if the mass production is much higher than the Flash laser radar.
At present, the laser radar scanner can be divided into two major categories of mechanical and optical formulas, and mechanical can then be divided into micro-mechanical, MEMS and SLAM.
SLAM is more rare, and the current product of the current market is micro-machinery and MEMS.
The micromechanical can then be divided into four small classes, which are rotary types (including rotary mirrors and polygonal scans), a Velarray, a multi-prism, and a voice coil.
MEMS is divided into two categories: MEMS vibration mirror and DMD microscope.
The MEMS spray lens can then be divided into three major categories of electrical electricity, electromagnetic and electrostatic electricity.
2, why is the MEMS route? Huge cost advantage
The development direction of laser radar is the full solid development of Flash.
Fareo is the only laser radar manufacturer of mass production customers. The long-distance car grade product SCALA uses a rotation mirror design, short-range products use flash.
However, Fareo’s next generation of long-distance Scala is MEMS laser radar, why?
Fareo laser radar development road map
Fareo is a laser radar gas-type turning laser radar nasal ancestor, but also the shortcomings of turning mirror laser radar, that is, the cost decline is limited.
The SCALA second-generation rotational mirror-type laser radar sold in French, the cost is difficult to be less than $ 400.
Here, let’s analyze the cost structure of laser radar.
Laser Thunder Mine can be divided into BOM cost, production costs, and research and development costs.
Let’s take a look at the BOM cost.
Taking Velodyne’s PUCK VLP-16 16-line laser radar as an example, its retail price is $ 3,800, and the BOM cost is about 1,000 dollars.
This is mainly laser emission diode and laser receiving diode, and 16 wires need to be 16 emissions, 16 receptions.
The price of the launch diode is typically $ 20-25, typically, such as Excelitas TPGEW1S09H, 905 nanometers, peak optical power 70 watts, 12V, peak current 30A.
The price of 1550 nano laser diodes is approximately 3-5 times the price of 905 nano-silicon laser diode, but its optical power is low, usually used in the field of laser communication.
In the laser radar, it is necessary to select a cost higher 1550 nano-fiber laser to reach the tile optical power, a total of approximately $ 580-740.
The motor and housing and the structural member are approximately $ 50, about $ 100, optical lens, filter and protective cover, and other optical devices.
Such a mechanical rotary laser radar is average BOM costs about 830 – $ 990.
In the main components, the two chips are more expensive.
One is the ADC08500 of Texas Instruments. This is a high-speed ADC, up to 500MSPS, so the price is more expensive, and thousands of procurement size is 30 US dollars, which is the product line brought by Texas Instruments.
The other is Intel Acquisition Altera’s FPGA, model EP3C16U 256C7N, with a price of approximately $ 14.
The back is mainly three chips, the main data processing chip Altera’s FPGA, the model is EP3C25F324i7, the price is approximately $ 22.
There are two memory, and the price is estimated to be only 5 US dollars.
There are also more expensive high-precision crystals, laser radar is a nanosecond product, and the clock accuracy is extremely high. The element precision is generally high.
The chip and active components account for approximately $ 80, and the passive element accounts for $ 15, and the PCB is approximately $ 5.
The figure above is the rotational mirror laser thunder in Freio Scala, with an annual output of 100,000.
Its BOM cost is approximately $ 300, and the 16-wire needs to increase 12 sets of launch and reception, which is approximately $ 400.
This is already the size of the annual output of 100,000.
This price is obviously a bit high.
For MEMS laser radar, the transmitting and receiving laser is reduced, even if it is equivalent to a hundred lines, some only one transmitted, receives a single-line SIPM, or the array can be used flexible.
The BOM cost is greatly reduced, and its main cost is concentrated on the MEMS spray, and the large-scale mass production MEMS spray mirror can be reduced to 30 to 50 US dollars, and the current purchase is 1,000 US dollars.
Based on the vibration mirror and the light source, MEMS laser radar BOM cost is currently about 450 to $ 1200. For Flash Laser Radar, there is no scanner, high-power VCSEL and high-performance spad are in a germination stage. The current price is very high, and the Flash laser radar BOM of 10,000 pixels is about $ 700-1000.
In the future, large-scale production can be easily reduced below $ 100.
So what is the shortcoming of MEMS?
The disadvantage is that the signal-to-noise ratio and effective distance and the fov are too narrow.
Because MEMS only uses a set of laser and receiving devices, the signal light power must be much lower than the mechanical laser radar.
At the same time, the MEMS laser radar receiving end is very small, much lower than mechanical laser radar, and the light receiving peak power is proportional to the receiver aperture area, which results in further decrease in power.
This means that the minimum signal detection capacity is lowered, and it also means that the effective distance is shortened.
The scanning system resolution is determined by the product of the mirror size and the maximum deflection angle, the mirror size and deflection angle are contradictory, the larger the mirror size, the smaller the deflection angle.
Finally, the cost and size of the MEMS spray mirror are also proportional, the MEMS spray mirror is MirrorCle, up to 7.5 mm, priced of up to $ 1199.
Sagitar Gongji Investment Section Technology Development MEMS microscopic mirror diameter is 5mm, and has entered a quantification period.
The MEMS microscopy used in the Pandargt 3.0 of Heroi Technology is provided by the Self-research team.
INNOLUCE acquired by Bailing can also be self-developed MEMS vibration.
MIRRORCLE product list, very clear, larger size, smaller the angle.
3, electromagnetic MEMS spray mirror: the best choice for laser radar
How to solve or improve this problem, that is, the electromagnetic spray mirror.
According to the different drive mode, the MEMS scanning mirror can be divided into electrostatic drive, electromagnetic drive, piezoelectric driving, and electrothermal driving.
The electrothermal drive is that the electrical energy is converted into thermal energy, and then converted to mechanical driving, the advantage is that the driving force and the drive displacement are large, but the response speed is slow.
The piezoelectric driving is to achieve the driving force, which has the advantages of large driving force and fast response speed, but the piezoelectric material is hysteresis.
Electromagnetic drives are driven by electromagnetic or permanent magnets, with large driving force and drive displacement, and disadvantages may be electromagnetic interference.
The electrostatic drive is to achieve the driving force in the charged conductor, which has the advantages of low power consumption, fast speed, compatibility. It is currently widely used.
Electrostatic drive is a mature manner, and the above MirrorCle has an Israeli manufacturer that is driven by electrostatic electricity.
Electrostatic MEMS spiral schematic
Electrostatic drive MEMS scanning mirror is made of single crystal silicon, simple process, low cost, very small chip size, low drive power consumption, and simple packaging, a voltage-driven device.
The disadvantage is that it is a bit small and is non-linear, and there is an adapted phenomenon.
The electromagnetic drive is large, and the electromagnetic drive MEMS scanning mirror also has a wide range of applications, and the scanning angle is large and linear scan can be achieved.
The electromagnetic drive device process involves the manufacture of the electromagnetic coils of tens of micron thickness, and the package needs to be configured to configure the permanent magnet, and the device module is slightly large.
The device is a current-driven device, and the drive current is tens of millimeters, and the driving power consumption is high.
The device can be operated only in a resonant state, and can also be operated in a non-resonant state. When the operation is working with the resonant state, the drive power consumption can be greatly reduced.
The disadvantage of electromagnetic is is that the process is complex, the threshold is high, the cost is slightly high, the volume is slightly large, the response speed is slightly slower, and the response speed is not a problem.
Because the current backend data processing capacity is limited, the laser radar data processing is now basically used in addition to the traditional algorithm. It also uses the laser radar to identify the target, integrated with visual sensors. However, due to the large amount of data, it is generally only 10 -15Hz frame rate, electromagnetic type can be 30 Hz, the electrostatic is higher, but the meaning is not large.
Another electromagnetic interference problem is easy to solve, that is, increase magnetic shielding and increased magnetic field density: using the most powerful magnet NDFEB, i.e., neodymium iron boron.
As for the problem of retreat, the root temperature of sintered NdFe boron is 312 degrees Celsius, the higher the currency temperature, the higher the working temperature of the magnetic material, and the temperature stability is better.
The eH grade NdFrosphere working temperature can reach 200 degrees Celsius, the lower H-card can also reach 120 degrees Celsius, enough to adapt to the car environment.
The reliability of the MEMS spray mirror has been taken as a attack target, saying that MEMS spray mirror is like a crispy potato chip.
The electrostatic may be a little bit this, but the electromagnetic type is different, its volume is large, the intensity of the cantilever can do, the electromagnetic spray mirror can do more than 300g anti-impact, 50g of the long-term overtime.
MEMS technology is generally adopted in military and aerospace, and the overload acceleration of more than 500 g can be affected.
The time limit of the application has been more than 30 years, and technology has gradually moved from military to civilians, not new technologies.
In contrast, the rotating electric machine used by mechanical laser radar has difficulty reaching 50 g of impact.
There are many MEMS products in the car, including gyroscopes, accelerometers, pressure sensors, MEMS silicon microscopy, Ar-Hud, and large lamps for DMD spray mirrors.
The DMD vibration mirror is an exclusive supply of Texas instruments, namely DLP technology. DLP technology has been used for more than 20 years, and reliability is not ink.
The Lincoln continent and navigator uses the early DMD chip DLP3030 of Texas Instruments, only 400,000 pixels.
Mercedes-Benz Ar Hud uses the latest DMD chip DLP5531 DMD chip DLP5531 (in the second half of 2018, so Lincoln is not used), the FOV is 10×5 °, the VID is 33 feet 10 meters, Mercedes-Benz called this equivalent 77-inch monitor.
Not only on HUD, the DLP projection is used, but on the headlights, Mercedes-Benz is also extremely luxurious to use DLP projection, but also DLP5531.
Projection headlights using MEMS microscope
Temperature is a DLP projection back book, naturally inseparable, the actual MEMS spray mirror can be seen as a semiconductor chip. The temperature range of the silicon-based semiconductor can be easily 40 to 125 degrees Celsius.
Mechanical laser radar used by rotary electric machines because of lubricating oil:
The oil is condensed in low temperature, and it is difficult to start or unable to start.
In high temperature state, the oil will volatilize to the mirror, and the number of recirculated reciprocities will be accumulated into oil droplets.
These two issues are generally existed in the current mechanical radar. Fareo has added PTC heating and cooling facilities.
For traditional cars, the vehicle regulatory is important, so select Flash laser radar is selected close.
For the new car factory, performance is important than the car, so it is necessary to choose Luminar, and the manufacturers between the two choose MEMS, such as BMW, although INNOVIZ is not smooth, but BMW does not give up the MEMS route.
Because of delivery issues, Innoviz must have to select electrostatic vibrators in the initial stage, but are turning to electromagnetic spray mirrors.
Comprehensive consideration, car, cost, volume, ecology, MEMS electromagnetic spray mirror laser radar is probably the best choice for most manufacturers in these five years. Note: This content is the author’s independent point of view, does not represent the heart of the car.